I don't want to go to work or school with my Sims. Why do I want to see my business Sim sitting for 8 hours filling out paperwork?
While I think the different heights is a great idea they'd have to really work on how to have two Sims of different heights interact. Different heighted Sims may end up kissing the other's neck or reaching to shake hands that don't quite meet.
I'd love to see better hair for men.
Assuming we will wind up with lots of custom content that was never meant to be (fairy ears in the glasses category) I'd love for this stuff to be geneticly linked. I mean if I had a Sim who had to wear glasses, it would make sense that their kid might need glasses too. So I'd love to see a bit of genetic link on things like this.
I love making fantasy Sims. So I love the elf earred face mesh. But what good are elf ears if 99% of the hairstyles hide the ears?

That is why I want accessories genetic linked so if I have elf ears on my Sim and they have a child they will have elf ears too without me having to decide which of the half elf/half human children will get their mother's ears or not.
And I want randomly assigned aspirations and attraction points. I have realized that most of my Sims have what I find attractive as their turn ons and turn offs. Gets kind of boring really when all my Sims are kind of the same. I should say this should be a turn on or off feature so people who like a whole city of romance Sims can play their game the way they want.
I have noticed that townie sims are more apt to be sporting my custom content eyes and hair. But not skintones. I'd like to see the game randomly pop out a mutant.
And since Sims can change into work uniforms when they leave for work or change into winter clothes when they go outside, how about letting us select vacation clothes or date clothes that they change into? Or randomly changing their outfit to other clothes in their wardrobe so our Sims don't wear the same thing all the time unless we make them change?