Why, after more than four years, do sims still lack distinctive personalities? (and other issues)

I'm honestly hoping that they'll do this in the Sims 5, since at this point, I really do not think they'll add it in TS4. I just feel like it would involve altering too many game mechanics and at 5 years into TS4, I just don't see them being willing to do that because of those factors. I'm sorry, I really don't mean to rain on your parade, I really do like these ideas but if there's a chance that at least some of these will be executed, TS5 is probably going to be that chance.