Oh, but Bones... let your imagination run wild for a minute!
Imagine a novel about someone like that, who has an accident - or an undetected predisposition to something like MS... and then has to deal with it in their own life. Heck, I know! How about a series of short stories that shows the DIFFERENT ways people deal with it and their differing attitudes?
I don't think it would be rude for you, in those situations, to remind the clueless person that just because you have challenges, doesn't mean you're stupid. I remember a student of mine in a wheelchair - god forbid anyone would hold a door for him! Such a tongue lashing would be delivered about how he didn't need any help, the poor person would be left in shock. Hubs used to slide chairs in his way, to watch him dodge them - it was their game - and hubs usually lost.
Attitudes are becoming more "enlightened" - but you know there will always be people who live under rocks... or have their own "challenges" about thinking about what it would be like to be in someone else's shoes.