My group got hit by this too in our last session. We had the same elemental spawning problem you described. It really just amounted to a minor annoyance for us, because it didn't appear until very close to the end and didn't prevent us from beating the quest. But you're right, we skipped over some potential treasure and just rushed to beat the end goal.
I understand why they're in the game to prevent you from taking turns strategizing too much and resting and healing. In a dungeon full of monsters, you likely wouldn't have time to rest, so I think they're trying to make it more realistic. However, since this is a game, I think the ability to turn it off or configure the timing would be a good addition.
RE: Quick tip about Descent: Journeys in the Dark with Road to Legend app