Fears already exist, in the sense of "do thing X with trait Y, get a negative moodlet". The main limiter here is that if your house is well decorated, you've just had a good meal, and you're wearing clean clothes, you'll overpower it with positive moodlets. That's just how the game works today.
Fears in the sense of anti-wishes that remove reward points? Maybe, but they work best with a sims 2 style where there's also a lifetime happiness meter. Having an unhappy or maladjusted sim can be fun in its own right. Being docked points feels like punishing the player, which is something that games should try to avoid.
