If I remember correctly, WG removed Northwest (a map I reliably enjoyed) because the north team won ~56% of the time. For the player in Random Battles, this means that for every 50 matches you played there, the outcome would change due to map imbalance…three times. Barely noticeable for almost anyone not in the top 0.1% or playing some kind of competitive mode.
What North West did well, and what many more "balanced" maps currently in the game fail to do, is provide a place where every vehicle archetype can do well. A 56% unbalanced map is only painful 3% of the time (since half the time the imbalance will be in your team's favor–and even then, it's hard to tell when a loss comes down to the map or the players), but you know what's painful EVERY time? Loading into Mines in a stealthy TD, or Prokhorovka in a superheavy, or Paris in a light tank, or Himmelsdorf in a SPG.
Maybe my judgment of Northwest is wrong, but my point stands. This is a game; we play it to have fun. For a map, "imbalance" between teams–within reason–has only a small effect on fun. But a map where, because of your un-swappable vehicle, you can only choose between a fight at huge disadvantage or sitting somewhere uselessly for minutes on end waiting for someone else to decide the match, has a LARGE effect on fun.