I make a lot of platformers, but I do very little character-work. I think it's very important to me to acknowledge the player on the outside of the screen; you're a real person playing this game. So who are you? I want to give you the tools to be yourself in here. Do you embody the character better when you can see the character or when you can't?
I have trouble designing UI because there's nothing for you to embody. You're a person at a computer, doing computer things.