Make spellcasters actually exist in the game?

I believe the reason they are not using too many toggles is because it causes instability in the game. I'm pretty sure that's what I read from one of the devs. When you think about what toggles actually do, they change the course of the game. The more toggles you have, the more game shifts and combination of possibilities need to be considered, and the game needs to be programmed for it. When you have people trying out features and then toggling them off, the game makes that shift and it surely affects a bunch of game code. With everything else going on in a Sims game and the more heavy weight of packs, you start risking more issues and bugs as it is. Adding too many toggles most likely becomes the straw that breaks the camel's back, so to speak.

If you look at how heavy Sims 3 became in only a few years, and how many crashing, freezing and corruption issues it had, it's an example of what can go wrong when you try to do too much, too fast, with too many possibilities.

So I think they've been reserving the toggles for more major and important features, to use sparingly, which is why the main Occults come in separate packs to begin with.