But people with crutches or with some kind of coordination difficulty would be entirely unable to use the door, which would be a problem if it was a toilet.

Ooh, I just had an idea. Somebody ought to build an art exhibit where to get in, the doors are all incredibly thin or with complicated handles that you need more hands than you've got to open and unacceptably high up, and there are massive giant steps up to another level - and then there are sane ways of getting into it, but you have to walk all the way around the entire exhibit to get to the first door, then all the way around to get to the second one, then to get to the sane staircase you have to walk all the way round again...and then in the middle there are models of all these incredibly tall thin people with several arms, and a little button with a picture of a normal person and "press for assistance" on it.

The Tate Modern has a room for people like you...

I always thought the room for people like me in the Tate Modern was the toilets :) they're shiny and black.