I'm one of the hardcore Sims 3 lovers too (even though I play TS4 a bit), I've noticed as you say that many people want Sims 3 EPs to return but almost everything that could be done in the Sims was done in TS3. So it can be hard now to find truly original ideas.
About the rest, things that are also Sims 3 features that people want back, like more complex personalities, free babies, seasons, pets, open worlds, CASt, less cartoony graphics... Do people want them back because they were in TS3, or do people want them back simply because they're realistic details of the real world ?
Personally, if anew game just happened to be TS3 2.0, I wouldn't buy it. I already have TS3 ! No need to spend so much money for a clone of a game that already exists.
Every new Sims game needs to have new and original features. But TS3 added a high number of realistic features. And as we like some realism, it's normal that we want this realism back. It doesn't need to be done the same way as TS3 at all. But one thing is sure, it shouldn't be neglected.