Yes, they're artists and this is their art, but software rarely -- if ever -- exists in isolation, yet DF acts like it does. You've all these nerds with too much time on their hands building all this ridiculously complicated infrastructure just to play the game in a way that is more comfortable, when instead the DF guys could simply allocate X amount of time and then be done with it. And this isn't a demand that the DF guys make the UI better, just a wish that they would put in a minimal amount of effort so that the community could hook in their own GUI code with a minimum of fuss.
Besides, I write code and debug fussy computer shit all day for work. Games shouldn't require that kind of advanced hackery just to play.
And who cares if they're artists? Neither the artist nor his art are immune to criticism (or, wishfully thinking, critique).