I hate the potion/barrier system in Inquisition. It might have worked if they had bothered to implement a proper tactics system and made the companion AI slightly better than useless, but as is, it's simply infuriating and not remotely enjoyable to play. The devs seriously need to go back and take a long hard look at Origins and try to understand why that game is so highly regarded.
The thing I miss most about combat in Origins is fact that they didn't class-lock weapons and armor. Why can't a mage use a sword or wear more protective armor? Of course they would have to rebalance by adjusting stats to reflect what class would be better with certain armor, but I think it's cheesy to lock them out completely from using it based on class...
I also miss the ability to have 2 weapon sets. I liked the ability to swap from a bow to a sword, or daggers... It makes sense in battle. If you're trying to hold a position against approaching melee fighters, you'd ideally want to to be able to inflict some sort of damage before they reach you. Or if you have a bow equipped and enemies close into melee distance, have the ability to switch to a melee weapon instead of firing a bow at them at point blank range...
I also agree that AI in combat isn't great. Seems like a pretty significant step backwards from DA:2, where you could prioritize companion abilities and set tactics based on a wide range of situations...
For the record, I didn't consider the combat completely terrible, but I did find it frustrating having to micromanage your companions on harder difficulties to keep everyone alive because they don't know what "Hold Poisition" means...
Let me stop, because this is a whole can of worms completely unrelated to this thread... lol