There are many things that need to be added to the game... I'm still peeved by the fact that relationships still haven't been fixed! Aunts/uncles, nephews/nieces, in laws, and cousins still aren't recognized correctly.
Also, the ability to change the intensity and color of a light while in buy/build mode (like in Sims 3)... I mean, is this really too much to ask for!?
I'm also still waiting for them to bring back cemeteries (with a working mausoleum that contains the remains of Sims who have passed away, like in Sims 3)... I'm sick of Sims dying from outside of my current household and being unable to find their graves/urns because they don't technically exist. Also, they need to stop ghosts from being able to act like normal Sims... it gets annoying whenever I see a deceased Sim dancing at a club or calling me on the phone like it's supposed to be "normal".
For those of us with 'Seasons', it would also be nice if we could view weather forecasts in other worlds BEFORE visiting them... nothing is more annoying than wanting to go visit a specific lot in a different world and then realizing the weather is completely wrong for what you wanted to do... especially when you plan an event ahead of time (yes, I know we could just visit the world prior to making plans, but we shouldn't have to).
I wanna see more trait slots for our Sims (maybe more around five, like in Sims 3). Toddlers can have 1-2, children have 3, teenagers have 4, and young adults, adults, & elders have 5.
There are still MANY things wrong with Sims 4 that I'm honestly becoming worried they won't end up fixing or improving... because we're likely approaching the end of Sims 4's life cycle (it's been quite a long time already). The fact that many of these things didn't come with the game to begin with speaks volumes about the development of this game... even including the content/features we've gotten through patches. The vast majority of this stuff should've already been included.