I would personally love it if they'd add disabilities in the game. I love everything that makes my game seem more real to me and disabilities are a real thing. I'd enjoy playing with really different kind of sims (after a while they all seem the same, because we have limited amount of careers and all the sims are same height and we only have 3 slots to build a personality etc. - skin tone and hairstyles and body mass doesn't really make a difference to me, as they do not irl).
I'd love to see my sim parents having a child with some form of disability, or that while at work you could have an accident and need to use walking cane/wheelchair for a while/forever. I'd love to see more than just erratic/gloomy/hotheaded personalities. How about one that causes dazed moodlets every now and then?
I'd love to see blindness and the need for a service dog! There's so many opportunities here for my games that if this was a pack I'd totally buy it. I'd love to build wheelchair friendly lots.
And for those who wouldn't want this in the game, I totally get you. There could be an option eg. to buy with aspiration points a cure for whatever disability you have if you'd like to reverse the change.