I miss having more than a few weeks between announcement and release, so everyone's theories and speculation were at least based on what theme had been announced, instead of constantly hoping for themes that might never come...
I do miss all of the romance actions from Sims2. I like the Sims4 makeout for taking pictures of my couples staring into each others' eyes between kisses, but the old makeout was so much steamier.
I miss all the childhood interactions from 2 that didn't need an object, like tag and mary mack and dancing on a parent's feet.
I do wish the teens had a little bit more differentiation from YA. I agree that university takes too long compared to normal lifespan. That's why I haven't bought DU yet. I am still weighing my options there.
But I never played 3 and the only difference in babies between 2 and 4 is that you can no longer bathe them or leave them on the floor all over the house. And you don't have to carry them to the fridge to feed them. So I don't really mind the babies.