If I look at other game franchises and how they have gotten better, it has mostly come down to finding a formula that works, and then build on it. Call of Duty got a huge boost when Infinity Ward made Modern Warfare, which then also resulted in Warzone. Sony got a huge boost with their first party titles like God of War, Ghost of Tsushima etc.
I feel that has often been an issue with the sims, Maxis haven't really found a formula that works really well, there is always something missing, or things are not working as well as they should, they have to spend a lot of time reworking things or patching things or improving things etc.
I think that they need to find a good base and establish what works, and what doesn't, and then build on that. I'm hoping with Maxis next game that they are getting enough time and resources to make something that fans want and that they also can build upon, we shouldn't have to wonder about ghosts, pools, toddlers, ladders, bunk beds etc. The game should support these things from the beginning or not be difficult for Maxis to make so that they could really build something good that fans want, while at the same time pleasing EA's shareholders.
If they manage to do that, then I think that The Sims could grow into a large franchise.
