4v4 will never be balanced in any RTS. Even Starcraft's balance falls apart in 3v3/4v4, because there's so much stuff going on the tightly paced game balance cannot keep up and all kinds of nonsense can pop up.
And no, this isn't ''4v4 players are subhuman cretins''. This is just a basic reality of how games are designed and balanced. 4v4 is a valid game mode, but it's not where the competitive gameplay happens because it's not balanced for it, just like, say, League of Legends competitive gameplay happens on the 5v5 map and not the 3v3 one, because the game's design is optomized to play that way. Ranked PvP in World of Warcraft is on 10 or 15 player maps, not 40 player ones. Counter-Strike competition is mostly in 5-6 player teams IIRC. So on and so forth.
Relic could do more, I guess. Ressource scaling and all that jazz. But it's obviously a lower priority behind balancing the game for 1v1, and 2v2 to a lesser extent.
This^.
I would like to add that a lot of people only bring up resource balance for 4v4 and say that lowering resources gained would fix it, but they are over looking something: Unit design. There are units in the game that are flat out made for 1v1 to 2v2 and will never be reliable in 3v3 and 4v4. Allies rely on early game light vehicle swarms, in 1v1 and 2v2 they have room to maneuver and are fully utilized. However in 3v3 and 4v4 what happens when you have to face a line of 4-8 Pak 40 guns and Grens with Fausts? The answer is that over half the units in the game are not made for 3v3 and 4v4. Realistically even with decreased resources you are still going to see the same infantry blobs fighting until heavy tanks, because light vehicles are just too unreliable for cost in large games on the maps we have now.
To balance for 3v3 and 4v4, Relic would have to redesign maps, redesign resources, and redesign units. Relic is still having problems balancing for 1v1 and 2v2, balancing for 3v3 and 4v4 is low on their priorities list. Also to whoever said 4v4 was the most popular mode, I thought recent statistics pointed that the most popular mode was 2v2 by a large margin over the other modes?