Why would someone spend $20 on a pack just to want 95% of that pack disabled? Beyond the scope of non-vampire CAS stuff and the standard build/buy content literally everything is built around vampires.
Just my opinion, but I would definitely hold off until a sale of some sort if you're just wanting the assets and not the gameplay. Expecting a toggle at this stage is a little unrealistic, there's what two supernaturals in game and neither are overly problematic. I sometimes wonder how people survived the previous two games, because every pack introduced a supernatural and a toggle wasn't available until the tail end of The Sims 3. Seems like a relatively new issue that wasn't a major problem in the past.
General rule: if you don't like what is being offered don't buy it. They aren't going to tailor their expansions so players can turn off functions that are added. As unrealistic, or out of place, as some players feel supernaturals are they remain a completely optional piece of the game.