Most people have no idea when to push and when to camp.
I was playing crappy F9 td-sniping map as a KV-2. A T29 or something and I moved toward the south chokepoint (we didn't have a TD platoon to camp f9). He pushes forward a bit, sees 3 heavies (none with derps), and decided to push into them, rather than let them come to us. KV-2 derp is pretty inadequate when it comes to slugfests; it depends heavily on surprise or peekaboo. There was basically no way we could push into that line of heavies. Bad time to push. Camp, let them expose their fronts. I'm running derp, I don't care that I'm shooting their armor at a 70 degree angle. I'll do ~300 damage a hit no matter what, provided I hit, which is not sure if I have to move backward and forward constantly at mid-range.
Conversely, even when a team isn't "lol let's camp spawn", you'll find that they often come to screeching halt the instant there might be an opportunity to shoot something. I'm starting to think that half the disruption of a suicide scout is that heavies and fixed-gun td's stop to shoot at it. I've played games where seeing a single heavy tank causes an entire blob of 8 or 9 tanks to completely stop in the middle of their movement; hello, you've just given the enemy your flank at no cost. If you're engaged in a movement, you need to complete it or abort it in a sensible way; stopping in the middle of the road with no cover after being spotted will get you murdered by arty when they are present. Often, if you're caught in the open as a heavy, you're going to have to push through fire to get to safety. Of course, you need to consider the flanks of your alternate cover. What tends to happen is that you'll charge past your lines into new cover and end up giving someone on the other side of the map LoS.
So many people playing WoT are incredibly passive that aggressive play is very, very disruptive and can be successful at times. If the opponent has well equipped and trained TD's, you're pretty fucked by aggressive play, though. If you're in a medium and run into a competent heavy blob, you're screwed. If your team is campy, you're screwed. If your team can't aim, you're TK'd.
I think a big reason things are so campy is that it's so goddamn hard to see TD's and, duh, they have high-pen guns. It seems like the only option much of the time is to flank them using terrain obstacles. I'm looking forward to the td camo nerf, if it isn't obvious. I'm tired of being shot by un-spotted TD's, despite being behind brush myself and not moving. It's sort of amusing that, once spotted, staying stationary means people can continue to shoot you after they lose vision; however, if you move to stop that, they might gain vision of you again.