I'd like to see clothing to be layered, and for sims to buy clothing from stores again and it being different price ranges. So they can actually save up money to buy that fancy dress or expensive suit.
But back to layered clothing.
Accesoiries categories could be the same as it is in sims 4. Belts could be added however, becoming seperate from clothing.
But basic clothing could consist of: Underwear (either a set or top and bottom seperate) then you have pants/skirts, tops or dresses over that.
Then you get a layer for vests, sweaters and other things to wear over the shirt or dress. And then you have the outermost layer: coats.
Depending how a sim is dressed, you'd see more of the lower layers. And it could even be a thing that sims with the snob trait or other traits think less of sims that have their underwear showing, wether it is underpants being higher than their pants or bra straps showing under a strapless top.
All clothing selected during CAS could have it's value detracted from the household funds that could be visible.
However, you could be able to select different financial classes for your sims, to make things easier or harder at the start. Ranging from dirt poor to filthy rich and various options in between.
Moving on to traits, I feel they should have more impact and there should be more negative ones. Default sims are so nice that the good trait is pointless.
I also feel like they should bring back sliders and have traits on top of that.
These sliders shouldn't come with points, they should just represent their disposition towards different aspects of life.
Sexual orientation could be a slider. A sim could prefer men, women or be a shade of bi. And a trait could allow a sim to not be interested in romance.
Shy/outgoing should certainly be a slider again.
Neat/slob too.
Interest in technology should also be a slider. At the lowest they won't even use phones, a little higher they'll use the minimum stuff for practical reasons but will turn to books and other things for entertainment instead of a television. And at the top they'd strongly prefer to use tech for everything and get special joy from purchasing advanced tech but can feel sad or angry when dealing with less impressive tech.
Also, sims should not have mobile phones by default. Should be something from buy mode under tech with several variations that cost different prices. I want my poor sims to not pull out a fancy smartphone.
Interest in children should also be a slider. At the lowest they hate children, and the further it moves up the more they'd like children and would want to have children of their own. In the middle they'd just be neutral on it.
Interest in celeberties should also be a slider. I don't want all sims to be obsessed with that and it shouldnt cost a trait for them not to be.
If they are super interested in that they could already be interested in minor celeberties, and the more famous someone is, the more less interested sims will take notice. The least interested sims won't act different even if it's a 5 star celeberty.
Interest in career should also be a slider. At the top they'd be a workaholic and might have trouble relaxing on vacations, and at the lowest they'd want to get rich and never work a day. More towards the bottom would be sims that prefer to switch jobs often.
Loyalty should also be a slider that determines various things. How likely they are to cheat on their spouse, if they'd be comfortable with job offers made behind their boss's back and if they'd toss a friend or loved one under the buss if they could benefit from it. The most disloyal sims could even enjoy betraying other sims. But the most loyal sims won't ever cheat on their spouse, boss or friends.
Intelligence could be a slider too. The dumbest sims could learn slower, be clumbsy, have a low brow sense of humor and struggle to use some objects. The most intelligent sims however might feel annoyed by dumber sims however and would tend to have more worries. But they'd learn skills faster. Still, it would have a downside.
Interest in the occult could also be a slider from the start. Those who aren't interested are skeptical and hate the sight of such beings, while the most interested want to become one.