Not sure about how exactly psi was implemented in Xenonauts, but in original X-com, aliens were supposed to only target soldiers that are/have been in their line of sight (aliens had temporal memory/vision of your troops for several turns after sighing). But due to buggy implementation once even one of your soldiers/vehicles got sighted the whole team could be targeted by psi attacks. Community projects like UFOExtender later fixed that, and made some additional tweaks, such as:
Alien Psi Attack Fix: Aliens will only remember the location of an unseen target for 1 turn. Of course, a successful Psionic Attack may renew this memory.
Without such fixes it was incredibly annoying to face alien psi, because it led to pure RNG: basically, anyone of your soldiers could have been psi attacked anywhere at any time. Also, it helped to incorporate Psi into tactics layer, instead of being above it.
Moving forward, I think, Xenonauts 2 should learn from this and implement Alien Psi properly.
I'm against having human psi abilities, but it's just a matter of preference: I prefer realism in tactics, and think human psi strays into power fantasy territory