@SimsSherry, I also really miss not being able to control the rest of your sims when one needs to go to the gym or something. It means neglecting the rest of the family so that one sim can fulfill a whim or part of an aspiration.
@Lisa46, I also wish the townies would stop disappearing. My sim had babies with 3 townies, who disappeared, but the kids remained.
@grimsoul, I'm glad you brought that up. The other day I was wishing so badly to just have a simple family tree!
Despite missing all of these smaller things, I think The Sims 4 fixed some major problems that, in the end, made The Sims 3 almost unplayable. (I was actually waiting 55 minutes anytime I wanted to load my Sims 3 game!)