More than anything I'd want traits and likes/dislikes to actually affect sim behaviour. It should be more than just a positive or negative moodlet depending on what they do.
Especially since they can only have three traits instead of five, it should do a lot more than in sims 3, not less.
Would be great if lazy sims could actually do any kind of chore faster but at worse quality, and take longer on the stuff they like. Could enjoy just lazing around in bed when they wake up, not getting out on their own unless they have work in an hour or have a need to tend to.
Should be able to lay on the couch while watching tv and do other stuff in a more lazy way. Being lazy could be a whole lifestyle.
A hot headed sim should enjoy fighting games or other stuff to blow off steam, they could be very sore losers in any game they play or any competition. They should not be so fearful, anger should be their first reaction instead. Angry because its raining, angry because they see a ghost, etc. They should be the kind who'd try to punch a ghost and it goes right through them, sims who act rashly in anger.
Evil sims should actually be able to do evil things, maybe have unique opportunities in any job that only an evil sim would think of.
Maybe be able to use some inventions for evil purposes.
Heck, I think traits should unlock unique inventions or other crafts that only someone with that trait can think of. Like only an evil Sim can build a doomsday device, only a lazy sim can invent a chair with build in snacks and drinks, only an active sim could upgrade training equipment to be more challenging, and a clumsy sim could maybe be able to make some stuff by accident sort of, but unable to replicate it at will.
Heck whenever a clumsy sim makes a potion or such there could be a small chance it ends up being something else instead.
For erratic sims, they should not be able to make any specific meal, potion, drink or such. It could always just be random. You could just select 'make breakfast' 'make lunch' or such instead. No sub-menus.
