The game really could use a hide option in CAS, letting you hide all the things you will never use. You could still view it by specifically picking the hidden things to show in the filters to unhide them.
With so many packs added over time it's just making especially CAS very bloated, it takes a long time to make sims in Sims 4. I am never able to do it in one sitting. And it's the picking outfits part that takes the longest. Not because I can't choose, I'm a straight guy with little fashion sense. It's because I have to wade through a lot of stuff I'd never use. Sure there's filters, but for me it would be way more helpful to hide what I'd never use since often I don't know yet what kind of Sim I want to make.
Anything hidden should not be used by random NPC's either.
I would not mind the option for buy mode either, though it's less bothersome for me there. I'd mainly want to hide a lot of hideous decorations to clean up that category a bit.