The problem is really the one that plagues all RPGs and would still exist without the armor concept (but is worse with it). Although you're encouraged to build a balanced party it's always better to stack certain classes. Rogues/Rangers/2handers /w rage are just the most obvious due to great weapons. A 3/4th mage party is just as bad as the dominant physical paradigm with like, 3 archers, or whatever.
Example:
Your party is an inquisitor and 3 mages (FIRE+aero or FIRE + geo).
high wits/int.
Port all npcs into same spot.
haste/Rage.
Fire ball/spontaneous combustion entire group.
Collect loot, move on.
It's what I'm doing right now and it's as easy as Rogue/Rogue/War/Enc was.
