all units in a M3 should have a 50 % less accuracy penalty because the whole idea of snipers shooting out of a vehicle is just stupid imo.
They actually do have a 50% accuracy penalty while the M3 is moving.
In response to OP, I'm not crazy about any of those ideas. Making guards come out later (which should happen in the new patch) fixes a lot of the sniper-related problems of the current patch. I'd also like it if the 221 was slightly more resistant to small arms, since that should be (imho) the go-to counter for snipers, sniper spam.