I freely admit that my understanding here is wrong and/or flawed but if I remember/understood the explanation correctly the point of the caps is to get both arenas to populate as quickly as possible. There's a critical mass for the arenas, game experience for a player in general will improve up to a certain point where you start to hit a point of diminishing returns. They may have even tried the uncapped split arenas but I don't remember for sure, but if I recall the point of the cap is to get the 2nd arena to populate as quickly as possible.
There's nothing wrong with the concept of caps. However there are serious downpoints in the implementation:
The second arena starts from nothing and grows slowly.
Why does the second arena grow slowly? Because most players see action on the full side and wait out or login/relog untill they get a slot there
- Or their squad is on the other side so they opt to try logging untill a slot opens on the big side.
- Both cases cause players to not choose the empty side and thereby delay the fill and further create the original problem