I honestly don't understand how vjek's setting the number of good/evil biomes, though. I haven't messed around much with the PSVs, as that just doesn't feel natural enough, is that what he's using? ...
It's possible either way.
This worldgen does not use the PSV interface/painter:
worldgen
Created in DF v0.43.03.
[WORLD_GEN]
[TITLE:YAL_PATCHW2]
[SEED:yQoayGoCIkuUkmm2GkSA]
[HISTORY_SEED:KkgQ2eiASgSiqgo8oG8a]
[NAME_SEED:aKMEeIwYs8AooI8aGMKm]
[CREATURE_SEED:SqO2KciAkcEY8Qu60ewU]
[DIM:17:17]
[EMBARK_POINTS:2500]
[END_YEAR:1000]
[BEAST_END_YEAR:1000:-1]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:1]
[ELEVATION:100:400:100:100]
[RAINFALL:0:100:3200:3200]
[TEMPERATURE:0:100:3200:3200]
[DRAINAGE:0:100:3200:3200]
[VOLCANISM:0:0:0:0]
[SAVAGERY:0:100:3200:3200]
[ELEVATION_FREQUENCY:2:8:0:0:0:2]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:2:1:0:0:0:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:1]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1]
[POLE:NONE]
[MINERAL_SCARCITY:500]
[MEGABEAST_CAP:0]
[SEMIMEGABEAST_CAP:0]
[TITAN_NUMBER:0]
[TITAN_ATTACK_TRIGGER:1:0:0]
[DEMON_NUMBER:3]
[NIGHT_TROLL_NUMBER:0]
[BOGEYMAN_NUMBER:0]
[VAMPIRE_NUMBER:0]
[WEREBEAST_NUMBER:0]
[SECRET_NUMBER:0]
[REGIONAL_INTERACTION_NUMBER:200]
[DISTURBANCE_INTERACTION_NUMBER:200]
[EVIL_CLOUD_NUMBER:200]
[EVIL_RAIN_NUMBER:1]
[GENERATE_DIVINE_MATERIALS:0]
[GOOD_SQ_COUNTS:289:0:289]
[EVIL_SQ_COUNTS:289:0:289]
[PEAK_NUMBER_MIN:0]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:0]
[REGION_COUNTS:SWAMP:0:0:0]
[REGION_COUNTS:DESERT:0:0:0]
[REGION_COUNTS:FOREST:0:0:0]
[REGION_COUNTS:MOUNTAINS:0:0:0]
[REGION_COUNTS:OCEAN:0:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:0:0:0]
[REGION_COUNTS:HILLS:0:0:0]
[EROSION_CYCLE_COUNT:1000]
[RIVER_MINS:0:0]
[PERIODICALLY_ERODE_EXTREMES:0]
[OROGRAPHIC_PRECIPITATION:0]
[SUBREGION_MAX:5000]
[CAVERN_LAYER_COUNT:1]
[CAVERN_LAYER_OPENNESS_MIN:100]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:0]
[CAVERN_LAYER_WATER_MIN:51]
[CAVERN_LAYER_WATER_MAX:52]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:10]
[LEVELS_ABOVE_LAYER_1:21]
[LEVELS_ABOVE_LAYER_2:2]
[LEVELS_ABOVE_LAYER_3:2]
[LEVELS_ABOVE_LAYER_4:2]
[LEVELS_ABOVE_LAYER_5:3]
[LEVELS_AT_BOTTOM:2]
[CAVE_MIN_SIZE:1]
[CAVE_MAX_SIZE:1]
[MOUNTAIN_CAVE_MIN:0]
[NON_MOUNTAIN_CAVE_MIN:0]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:2]
[TOTAL_CIV_POPULATION:0]
[SITE_CAP:0]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:0:0:0]
[RAIN_RANGES:0:0:0]
[DRAINAGE_RANGES:0:0:0]
[SAVAGERY_RANGES:0:0:0]
[VOLCANISM_RANGES:0:0:0]
However, this one does:
worldgen
[WORLD_GEN]
[TITLE:YAL_PATCHW1]
[DIM:17:17]
[EMBARK_POINTS:2500]
[END_YEAR:1000]
[BEAST_END_YEAR:1000:-1]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:1]
[ELEVATION:100:400:0:0]
[RAINFALL:0:100:3200:3200]
[TEMPERATURE:0:100:3200:3200]
[DRAINAGE:0:100:3200:3200]
[VOLCANISM:0:0:0:0]
[SAVAGERY:0:100:0:0]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:2:1:0:0:0:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:1]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1]
[POLE:NONE]
[MINERAL_SCARCITY:500]
[MEGABEAST_CAP:0]
[SEMIMEGABEAST_CAP:0]
[TITAN_NUMBER:0]
[TITAN_ATTACK_TRIGGER:1:0:0]
[DEMON_NUMBER:3]
[NIGHT_TROLL_NUMBER:0]
[BOGEYMAN_NUMBER:0]
[VAMPIRE_NUMBER:0]
[WEREBEAST_NUMBER:0]
[SECRET_NUMBER:0]
[REGIONAL_INTERACTION_NUMBER:200]
[DISTURBANCE_INTERACTION_NUMBER:200]
[EVIL_CLOUD_NUMBER:200]
[EVIL_RAIN_NUMBER:1]
[GENERATE_DIVINE_MATERIALS:0]
[GOOD_SQ_COUNTS:289:0:289]
[EVIL_SQ_COUNTS:289:0:289]
[PEAK_NUMBER_MIN:0]
[PARTIAL_OCEAN_EDGE_MIN:0]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:0]
[REGION_COUNTS:SWAMP:0:0:0]
[REGION_COUNTS:DESERT:0:0:0]
[REGION_COUNTS:FOREST:0:0:0]
[REGION_COUNTS:MOUNTAINS:0:0:0]
[REGION_COUNTS:OCEAN:0:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:0:0:0]
[REGION_COUNTS:HILLS:0:0:0]
[EROSION_CYCLE_COUNT:1000]
[RIVER_MINS:0:0]
[PERIODICALLY_ERODE_EXTREMES:0]
[OROGRAPHIC_PRECIPITATION:0]
[SUBREGION_MAX:5000]
[CAVERN_LAYER_COUNT:1]
[CAVERN_LAYER_OPENNESS_MIN:100]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:0]
[CAVERN_LAYER_WATER_MIN:51]
[CAVERN_LAYER_WATER_MAX:52]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:10]
[LEVELS_ABOVE_LAYER_1:21]
[LEVELS_ABOVE_LAYER_2:2]
[LEVELS_ABOVE_LAYER_3:2]
[LEVELS_ABOVE_LAYER_4:2]
[LEVELS_ABOVE_LAYER_5:3]
[LEVELS_AT_BOTTOM:2]
[CAVE_MIN_SIZE:1]
[CAVE_MAX_SIZE:1]
[MOUNTAIN_CAVE_MIN:0]
[NON_MOUNTAIN_CAVE_MIN:0]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:2]
[TOTAL_CIV_POPULATION:0]
[SITE_CAP:0]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:0:0:0]
[RAIN_RANGES:0:0:0]
[DRAINAGE_RANGES:0:0:0]
[SAVAGERY_RANGES:0:0:0]
[VOLCANISM_RANGES:0:0:0]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_EL:100:100:100:100:100:100:100:100:100:100:100:400:400:400:400:400:400]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:0:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:0:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
[PS_SV:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100:100]
Yet they both produce the same kind of world, using the same technique.
In the PSV version, the medium region in the SE is painted with elevation, and the rest of the world is good/evil, ideally in small biomes, which tends to be true pretty much all the time.
However, the non-PSV version has more variables out of your control. Procedural savagery placement and elevation mesh and weights don't always produce what you want. From my perspective, if you're doing advanced worldgen anyway, you might as well use the PSV tool if required.
Pure patchwork worlds without using tricks like the non-savage, non good/evil medium mountain block shown above are harder to do. Why? Because even though you can randomize elevation, you're just increasing the odds of there being a savagery/good/evil overlap, leading to a rejection of that world. From a time & efficiency point of view, you might as well just make it work all the time.
Also, it seems that most players don't really like embarks that are non-flat. It leads to thicker embarks (farther to path to the magma sea), more scrolling around during gameplay, and a less ideal location if you want to build an above ground fortress of a particular size and layout. Of course, some players don't mind a few z-level changes, but purely flat is typically more desirable.
So, if you can control the elevation, and leave the rest of the world flat, that seems to be better. Some of these reasons may seem a bit overly specific, but sometimes what people want is a long list of things that are often mutually exclusive or rare, individually. So, in some cases, I've found an ideal worldgen, but it doesn't have an aquifer. Or the player only wants bloodthorn in the caverns, or they want it steel friendly and no surface trees. Or all of these, plus all races on embark, or a dead civ on embark.
On top of that, any rejections (even 1) makes it so worldgen is not identical, cross platform. So it has to work, reliably, predictably, cross platform, and meet a list of arbitrary requirements, and not suffer FPS death or be unplayable, performance-wise. Challenging, often.