TBH, I don't necessarily think two sides wouldn't "work", it very well may, but it's way too risky to even attempt it.
Advantages:
You can't hide from a particular squad by going to other side of map.
It simplifies strategy to where it's easy to understand exactly what is going on.
Roster numbers will be more of what you see is what you get. You won't have the high number side being ganged on both fronts, or the low numbers side only ganging on one front and being ganged on the other.
Disadvantages:
Unbalanced numbers are extremely more damaging to game play. Not only that but it could easily create a domino effect of players migrating to the "winning" side because no one wants to play on a losing team, except the vet heroes.
Redoing every single map for a 2 player game. Would take an incredible amount of time.
You are taking away something and adding nothing of quantifiable value to the game. Bound to piss off a lot of people when something is taken away.
You run the risk of creating much larger concentrations of players into condensed space. You might end up having a mega furball with 100 planes. Sounds cool to me as a vet, but the new player stands no chance. NONE. Neither does the guy with an average computer.
All in all, it's not even close to being worth it.