As just mentioned on another topic, I miss the yoga sims could do. I also miss bathing babies. Everything about babies in Sims 2 was better, except that you couldn't see their motives, though some would argue that was better since it was more realistic. I really, really liked how genetics in Sims 2 made a lot more sense. There was no random variation like you see in Sims 3. A little variation is nice, but I think there's too much. Not every baby should be a mutant.
I miss having a gardener, but I don't miss having to water flowers. I miss aliens. It's a shame those haven't returned so far. I really liked sewing in Sims 2 also. Since you don't have to purchase every outfit in Sims 3, it wouldn't be the same, but it would be nice to have anyway. I also kind of miss the aging in Sims 2. In Sims 3, it's hard
not to have your sim live forever. You have to actively avoid certain things. In TS2 it was easier for me to play generation after generation because of this. Although I was a teenager when I played Sims 1, I hardly remember it now. The one thing I remember is that it was actually really challenging to achieve what you wanted. You couldn't walk right up to another sim's home if you wanted your sim to meet them so they could eventually get married. You had to get lucky with a walk-by. Sometimes it seems that, while time-consuming or intensive, it's not really challenging to achieve in TS3.