Psionic force field being invulnerable makes no sense...

[Tamiore]

From lore standpoint, it does not make sense that a lvl 3 character with a bit of psychokinesis training can conjure up a barrier nothing in the world can bring down (not even another psion with much higher skill). But lore is really a minor issue here, the major one is:

It's not good for game-balance to have abilities that cannot be interacted with in ANY way. I can't think of anything else in the game (be it ability or consumable) that has literally no counter and simply can't be interacted with. All other area denial tricks can at least theoretically be countered or rendered moot by the right combination of enemies. Force field can literally stop anything, including an army of psions each with 10 times your skill in psychokinesis. And the situation will only get WORSE when temporal manipulation will be introduced (because PC will be able to lower force field cooldown).

Long story short, I really think force field should create actual in-game tile blocker with both duration AND hitpoints.
For example: each section of the force field will have hit points equal to the invokers effective psychokinesis skill, while being immune to cold/heat/bio/acid damage, having TD of half the effective psychokinesis vs mechanical and energy (and maybe having some special interaction with electro, like making electro actually restore it's hitpoints). On top of that, let's say that every psionically capable entity will be able to deal guaranteed mechnical damage equal to it's effective psychokinesis skill to the force field (for 20 AP and 5 PSI), representing a concentrated effor to dispell the thing.
These numbers are, again, just an example. But I really think force field should stop being complety non-interactive for enemies for reason outlined above.

[harperfan7]

I think this is why enemies never use it. I have to say I think I agree, but I haven't deeply thought about it yet; there may be a reason why it's okay.