There has been other issues with vehicles in pvp4 due to creative use: People using them as one-way Shields (shoot out but be protected against hits from outside), unorthox nagivation to make them travel (ie fly) faster than expected. I'm not sure if exiting vehicle, shoot with rocket launcher or Another hand-held weapon mid-air and then jump back into vehicle is an issue or not when it comes to fairness.
Besides then the "other side's" use of them to recall stackables to storage.
The problem is that when there is some sort of abused feature, some people doesn't listen, but MA forcefully need to disable a certain feature to make those people stop (ab)using it. "It's MA's fault we can still <trap mobs or whatever> and I'll keep on doing it".
Having said that, as someone else mentioned, there is still places for vehicle pvp; oil rig, landgrabs and pvp3 to mention a few. (How many more tank- and battleship Blueprint clicks have been released recently?)