It depends on how small the domes are actually going to be. Some monsters greatly benefit from being very close (Behemoth), while others benefit from being far away (Kraken). If we are restricting space, we are also restricting options. I understand the want to have more fights, but some characters could have their performance compromised due to the smaller spaces, or vice versa.
Plus, this makes the importance of perfect hunter play all the more important. If you watch some pro evolve hunter teams, they tend to spread out, covering a large area. Sometimes covering entire sections of the map. If you’re making the arena smaller, you give a team less to worry about, they don’t have to care about watching as much space. And thus, making their job as a hunter easier. I would also like to mention god domes, as I think this would give monsters less chance of avoiding the damage that hunters can put out from those positions (less line of sight breaks and yada yada).
I’m not saying that this won’t solve the problem, it’s just a few points I’m looking at right now.
Alongside some other changes to the game, I could be a bit more agreeable. (Things like movement tweaks come to mind.) But not in the current state.