About elitism:
I always forget how smart people are here. My last post had a hint of overreacting in it. The occasional rude comments on the forums don't make it elitist, they just stand out (and are remembered), because generally everyone are so fair.
I just hate elitism, so I think it is a very important thing to discuss and prevent.
About Commercial DF:
The discussion here is just like talking about underground/indie bands. The large record companies don't sign them because these bands usually differ too much from the music that sells a lot.
I really love art (or other creative things, like DF) that are truly original and bring something new or different to the world. Large companies don't care how groundbreaking the thing they sell is.
DF is too different and unfinished for companies to start selling it in a large scale. But if it happened (or the playerbase became much much bigger in some other way) it wouldn't ruin the game for the majority of people, but like it happens with bands, some of the original fans would think that something important was "stolen" from them when it wasn't just their thing anymore, and maybe even start dislinking it.
The constant learning process (and the starting learning curve) of DF is very important reason why I like the game. Like Akroma said (and I agree that it is good), the learning curve filters out the people that are not into games like this. The learning also binds the community together because everyone has at some point gone through the hardships of the UI. If the learning was made a lot easier this would be a very different game. When people have invested much time to learn to play the game, they are more likely to keep playing, so that their investment doesn't go to waste. These among other things like the constant presence of Toady (and his enormous detail of the development process) make the game a much more personal experience, which makes the people in the community much more enthusiastic about the game.
Writing this I understood how big part of the game the community and the presence of Toady in it are.
Without the personal aspect and the community the game is still great, because of it's mind-boggling details and overall sheer awesomeness, but the personal parts make it the best game ever.
If DF became massively big, it could make it less personal. So I will have to agree with lumin that commercial DF would be a disaster if it was also simplified.
TL;DR (DF is great and original because it's personal. Commercial DF could be less personal and therefore worse)
P.S. Sorry about the confusing text, it's hard to express thoughts clearly with a foreign language.