to me its a functional choice. compare something like word *gag reflex* or openoffice writer, to emacs for example. the former are much more user friendly, admittedly focused on producing written text, while emacs is chaos for someone who first opens it. but emacs is immensely powerful once you learn it - word and such have a much more steady curve of improved usability. you start off a lot easier but you cant do things a LOT faster once you learn it and not terribly easier either. i value the style DF has for control because i favor the emacs approach since its more rewarding in the long run and i dont have a problem spending time learning it.
the same could be said about the representation of the world. DF already gets serious fps hits from all its fucntional complexity even with the sdl library which uses opengl, which AFAIK means it uses the graphics processor to do the painting, saving the main cpu from all that. even if you could claim a strongly graphical interface wouldn't impact the cpu itself, it still has to perform the calculations necessary to tell the gpu what it wants. the way DF is made, its representation is simple enough to code and saves all that extra overhead. i do believe that if improvements and optimizations are made it can run all the stuff along with a decent graphical interface (like a lot of commercial games do quite successfully) but it would still require more processing power from the gpu (which if you dont have, makes it a problem) and to me it feels like a waste tbh, though understandably i'd be in a minority on this.
looking at this thread though makes me think we've developed a certain mentality on bay12 that doesnt necessarily help newcomers lol - summing up the usual form these threads take could be done like this:
new_guy: hey DF is awesome, but all the bugs make it hard to understand, there's little help from the game and that interface is so hard to use!
(3 seconds later)
dwarves: *walls of text*
new_guy: but...
dwarves: *walls of text* *topic derailed*
new_guy: *crit* (signs off)