First, bugfixes:
1. (new in current version) Kobolds get the ability to survive without food or drink. (Prevents kobolds from dying out in worldgen.)
2. Whips get toned down to something approaching reasonable by reducing their size. (Minimizes the "bullets with handles" problem.)
3. PET_EXOTIC becomes PET in all RAWs. (Prevents the "you can't tame anything you catch, ha ha" problem.)
4. (new in current version) [GOOD] and [EVIL] trees and fruit-producing shrubs have these tags removed. (Fixes "no sun berries" issue.)
Then some flavor/balance changes:
5. Cinnabar and Cobaltite become iron ores instead of useless ores. (Prevents "low scarcity, but no iron" issue.)
6. All soils are both sand and clay (plain earthenware). (Prevents the "no glass/pottery industry here" issues.)
7. Aquifers are disabled. (Prevents the "I don't want to see another aquifer again, ever, because they aren't fun." problem.)
Then some QoL additions unrelated to the RAWs:
8. Soundsense is installed. ("DF is much better with it!")
9. Reveal is permitted to prevent unexpected penetrations of magma/groundwater/caverns when designating. ("Stonecunning")
10. DT is installed and used. (See "Soundsense", above.)
If I want to embark somewhere without iron, that's easy to find/generate in the current version. No clay or sand? Also easy to get. Being able to create the "all resources available" spot which is also an Untamed Wilds area next to a volcano? Not so much, and I don't want to stare at the worldgen for that long. I want a site where success or failure is MY fault as a failure to plan, not a feature of the available resources being unavailable or insufficient.
Recent changes to worldgen and site finder (no layer ID before embark) are like a big, big middle finger to me as a player, so I feel no remorse in avoiding the problems they cause through external means. DF is a sandbox. If I want to limit my tools to make an embark
harder to survive, that's cake. If I want to make an 'ideal' spot, though, it's much harder to generate (without reducing the world to featureless plains of one terrain type, etc) an ideal spot (and find it later).
Vanilla DF is a big draw, people like the game, but they may not like one specific bit. Rather than saying "deal with it", you're able to mod it. Whips are overpowered? Tone them down! Badgers ruining the game? Remove them! Goblins not challenging enough? Make them bigger! You can tweak anything to suit your tastes, and I think that gives it a lot of appeal. A game creator's vision might be a good one, but you can't please everyone with one layout. Being able to change the layout makes it possible to appeal to almost everyone.
Also, this.
It's not just "I don't like that", but "I can fix that buggy behavior by doing THIS" sorts of things that really sell modding to me, though. They allow me to put up with constant breaks in behavior caused by versio increments by fixing the underlying issues in the RAWs.
(Also, a BIG shout out to Lazy Newb Pack here, because without that, my lazy butt would long since have stopped playing DF, as constantly reinstalling gets old fast.)