I was thinking how awesome it would be to include in a future version of the sims (or even patched into Sims 4) the ability to design your own traits, aspirations, and careers which you could then share on the gallery.
It could be a separate program outside the game provided and designed by EA to work hand in hand with the main Sims game. You could choose what buffs a trait would create, the steps needed to complete an aspiration of your creation, and the goals for a rabbit hole career (maybe even the "choose to work from home" careers).
They would then be compatible with the game and the program would be updated with each update. Right now we have mods for these things but they often break with updates.
Currently many people complain about not having enough careers, traits, and aspirations. This would provide players with an endless supply to choose from and make the game more customizable.