For some reason this question really sparked my interest. Let me list all the good examples I can think of before I give my shameless self-plug.
Since all Twine games are based on text and hyperlinks, I could argue that every Twine game uses UI as a form of expression to some extent. Some notable examples:
Even Cowgirls Bleed: Play this one on a computer, not a mobile device. The player triggers hyperlinks simply by hovering over them, and this is used to evoke the feel of being a reckless, trigger-happy woman.
Depression Quest: The game disables certain player options based on the protagonist's emotional state. It's a powerful metaphor for going through literally debilitating demotivation.
Everything You Swallow Will One Day Come Up Like a Stone. The player only gets two buttons, + and -. The significance of the control scheme is more ambiguous in this one, and I'm not totally sure how I'd interpret it.
Content warning: the game is about suicide.
Aside from Twine, Inkle did a podcast episode about UI in narrative games:
Soundcloud link. I haven't played their games except for part of 80 Days, but it seems like they would be good examples as well.
Lastly, my game (The Whisperer in Darkness) is text-based and does a bit of (hopefully) cool stuff with typography. I haven't mentioned much of it in the dev log, but if any of you would be interested in that, I could get into it with the next post.