I saw that in a list of new fears and thought "that doesn't sound fun".
It's kinda annoying how many of my sims developed that water fear that made them tense when they went swimming (and one guy got tense in his own home, when he wasn't even near water). But now they added a new fear of water and a bunch of other fears.
Why would fear of fire increase your chances of accidentally starting fires? My rl mom is afraid of fire, and that makes more careful to not start fires than people who don't have that fear. So why would fear of fires make sims more likely to start them?