It may have to do with money. DF is free while the big budget game costs 60$. Who would not expect perfection when the game is that costly. Also, the interface in DF while horrible has a reason to be horrible(due to the game's depth) whereas usually in AAA games the interface is fucked up just because they wanted it to look pretty
You are most likely correct about players's expectations.
But I do disagree about the DF having bad interface due to depth. Depth, complexity and good interface are not mutually exclusive.
ASCII and good interface
are mutually exclusive, though. No matter what people claim, when comparing the infinite possibility of simple graphics vs the limited possibility of ASCII, ASCII loses. A lot of ASCII fanboi 's will disagree, sure, but when you actually consider the mental load involved, ASCII will (almost)
always lose to pretty much any other choice. But fanboys ignore logic by default, so all the HCI and human factors research in the world will never convince them they are wrong:-)
And in the case of DF, although you can use tilesets, the tilesets are limited by the ASCII backbone negating many of the benefits.
EDIT:
Oh, and Skyrim's interface is inexcusably bad, for no good reason at all (considering skyui and other mods fixed it almost immediately, at essentially no cost) except porting benefits. yet people here forgive it and buy the game, the big budget AAA game I might add.