Cooking in base game needs yet another overhaul as the hire a cook is broken for years now and they haven't fixed it. I also wish some of the recipe ingredients could exist in game such as corn and hay as growing crops, as well as chicken meat and other realistic options. We should be able to make flour as well (maybe in a paid DLC though?).
Color wheel for CAS including hair, eyes, makeup and skintones (not including clothing)
Heterochromia in CAS
Game time speed overhaul so we can have more time for Simday to do more than Sims taking hours to eat, take a bath or shower and taking care of other basic needs and then going to school or work, not enough freetime in game.
Wheel chairs and more appropriate acknowledgement of disabled people in game, and new accessibility options, including ramps for houses and public community lots and worlds. (There was a potential hint for wheelchairs/disabilities updates in High School Years by the way; you can see a car parking with the wheelchair symbol there)
New basegame traits and at least 1-2 more trait slots for Teens/Young Adults and older, as well as maybe an overhaul for less personality-defining traits such as Lactose Intolerant and Vegan, they should make a Sub-Trait/Side-trait category or something, as I do not know of any person who defines their main personalities as being allergic to milk or being vegan)
Family tree overhaul
Cars and buses
Base game bikes
Spiral stairs
Preteen life stage
Mid Adult/Older Adult life stage
Online dating
Landline phones and setting to only use landline phones in certain game saves and turning modern smart phones off (medieval/centuries historical game challenge?)
Newspapers
Burglars and burglar alarms and option in settings to toggle them off for players who don't want them
Upping the 8 Sims max household limit, preferably to 12 or 18 minimum so we can have proper horse farms and cats and dogs with Sims
Attic room tool
Reading Skill
Museums overhaul (as @kemowery stated above, so much yess! We need that at some point <3)
Real estate overhaul which means now Sims could own more than 1 home lot in-game, as well as buying shares for public venues or even buying them with enough money.
More emotions and an emotions overhaul so it won't override everything else in the Live Mode while playing the Sims
Curved swimming pools overhaul
The reintroduction of Missions/Opportunities from The Sims 3 base game. I feel like Odd Jobs aren't the same thing.