Ok so 2019 is well, upon us...
Sims University as far as I am concerned should be a priority, I loved in 3 the upbringing bonus traits it introduced, the boost to careers dependent on degree's you did, the new skills (Billiards, Darts, think there was even Cards). University provided a missing link in a Sims circle of life that was well amazing and fun to play and experience.
Things that I think are missing and would love to see;
Salons and Barber Shops, which lead to better Sim creation (see below), imagine going to a Hairdresser to get streaks through your hair, manicured nails, party make-overs (multi colored eye-shadows), a pink tiger face paint?! Bikini wax...
Considerably better Building options, terrain manipulation, ponds!!, color selection and blending, themed color building, I can not remember if it was in Sims 3 or below you used to be able to go to a color template and customize your colors for pretty much everything, then you could down load stencil patterns with 2 or more color options, literally to create a very unique look for wall paper, hair, make-up, even skin... not to mention being able to create a literal mosaic for a feature wall in a house. Install patterns that can be used on furniture, (a kids couch with Disney characters on it, while the exact same couch is also in the guest living but the seats look like the solar system, not to mention the frames are different yet again).
Yes I spend hours in creation and building, I look for a theme where I can but often am limited due to color selections and designs (patterns). I would love a wall paper that matched perfectly marble tilling, let alone changing the white Marble so the grey looks electric blue as an example.