This suggestion is not asking for new or improved vehicles, but instead attempts to address the issue of PVP players making bases nearly impenetrable by simply spawning in a Tarantula, deploying an AFV6 AA, and then spawning again, etc. It is incredibly easy to build up a pile of AA, and resupplying said pile with a nearby Munitions Container or two. The sheer volume of missile and gun fire can easily destroy all incoming enemy missiles, be it missiles, bombs, nukes, or cruise missiles, and the only thing that sometimes gets through is an ARAD (not useful when attacking a base that has other things like hangars still available) and of course railguns/other gun-based weapons.
There should be a limit to the number of vehicles a single player can deploy while using a Tarantula, or a limit on the number of AFV6 vehicles that a faction can operate at a time, or simply an airbase region cap on the number of vehicles in said region. In the handful of games I've played so far since 0.29, about half of them had bases with absurd numbers of AA vehicles. Of course, there's a limit to how many a single player can put due to the cost, but it's really not much for a single AFV6. Running just one Compass mission can sometimes rack up enough money to deploy over a dozen of them...