It's always been such a complex issue. I'd love to be able to have my condition in the game so I can portray myself accurately, but at the same time I can 100% understand all the concerns posted here. If they did add anything to this capacity then making it optional would most likely be the best way to go, so those who want it can use it and those who want to get away from that sort of thing can. I use mod traits that serve the purpose I want pretty well.
My main issue though is that I wouldn't trust the current team of developers with something like this. After seeing them handle other things in a less than efficient fashion (not listening to the community in certain cases, constant technical hiccups) I don't think they'd be able to pull this off in a suitable way. I can also see how this element of real life wouldn't fit with the rest of the game's less serious atmosphere. The game isn't mature enough to really handle this kind of thing on an official level.
Maybe if they invented unique conditions for Sims that aren't present in real life they could get around some concerns, I don't know.