Regarding the graphic. I like the one on the right, and think it would be neat to see that kind of topography in the game, but you shouldn't be able to just paint your embark site. Dwarf Fortress is about surviving in a harsh and deadly world, not the world bending and shaping itself to compensate for the skill of the player.
*eyeroll* It has nothing to do with skill. I've been playing long enough to easily survive on a 5 layer aquifer glacier or whatever with no metals at all and a single pick and some pigs, if I have to.
The issue is that once you learn how to do that, "harsh environments" almost instantly lose all their charm, because there's nowhere to go from there, other than very icnremental silly self-restrictions that just feel arbitrary and unfun to me personally. In fact, ironically, the LACK of realism at the limits of the game are precisely what stop harsh environments from progressing into further challenges. For example, the fact that undergroudn tiles are always 10,015 urists of temperature makes it pretty much irrelevant what the surface temperature is. You can embark on a fat boilingly hot map, and as long as you can dig a tile before you die, you're good for the rest of the game, and it's no longer any different than any underground only fortress after the first 5 seconds... You can't even mod the game to MAKE it different if you want to.
Now, I just want to build cool forts, elaborate traps, megaprojects, and !!science!! labs, and tediously trading for 5 bars of iron per year does not lend itself to being able to do those things without severe, unfun annoyance. Or, for example, going to the boring trouble (to me) of buildign the same old hum drum pump stack or piston EVERY stupid map. It's always the same. That's boring. Just give me a volcano and let me try out my new magma experiments right off the bat.
For NEW players, they'll have fun building their first pump stacks, etc. Hence I'm not suggesting changing any default situation. Only a fairly high end world customization non-default tweak.
It is under my understanding of the devlogs that Dwarf Fortress is aiming not to be a fantasy game, but a fantasy world simulator. While this idea does sound good, it does not fit within the goals of the development effectively.
Your premise does not lead to your conclusion, in my opinion.
What is it about painting my own embark map that is NOT simulating a fantasy world? I'm painting my fantasy world (or a portion thereof, the rest being generated according to Toady's fantasy)... and then simulating it... Thus, I'm still simulating a fantasy world.
It's not even any compromise to roleplaying -- I'm simply ensuring that a location exists that I like. Once embark begins, it's just part of the world like any other. And, being a FANTASY world, there aren't really any rights or wrongs.