Primarily due to Relic only having limited resources: I believe 4v4 should be a fun extra in the game and nothing else, and left to the players to set up custom map lobbies with mods and their own rules for team games. It should be a fun zone where people have fun, and don't take it too seriously.
1v1 and 2v2 should have been the full focus of the game, Relic's resources were over taxed as it is, and we end up with the worst scenario of just average game modes instead of two really amazingly polished game modes.
I don't entirely agree here. 1v1 and 2v2 are indeed the more serious game modes, but I doubt the average playerbase is really that competitive. I think a large majority of players is social minded and wants to have a good time with friends rather than playing small competitive matches. I personally enjoy the tactical and strategical aspect of 2v2s, but playing with my friends in a 3v3/4v4 is way more fun and relaxing. And imo these modes still require proper balance to be playable.
I do think there should be seperate balance for different modes, like unit limitations or tweaked unit stats (for example Su-76 that is fine in 1v1/2v2 but is too cost-effective when spammed in team games). That does however put a strain on company resources like you mentioned.
From lower people, who love to camp: Port of Hamburg and Hill400
I think Hill 400 is actually a nice map, for some reason we usually have epic matches on that map. It's big enough to flank while still concentrated around the middle (fuel cutoffs). I don't think it's that campy at all.