So I allow them. I think they fit thematically.
However, I also use them. My players are very wary of their mental stress tracks.
I've also made provisions for mental defenses. Specifically, I allow Alertness to defend against our Illusionist's mental attacks in addition to Discipline, and let it boost it (other types of mental attacks are decidedly lawbreaking, but his work on distraction and disorientation). Combat is quick and dirty.
However, we've been fighting the white court, old school necromancers, and some black court vampires. Mental stress is a two way street.
Against other types of monsters, they know it's a risk. Zone wide mental attacks seem to be the biggest problem, but they also shut down the whole party so we're pretty good there. Single target attacks are very effective.
Still playtesting it though.