Piwbl, just about BMGs... not sure if you ever sat in one of those. You have very poor vision and X/Y axis mobility. You are limited to ironsights rather than main gun aiming devices.
In short: you give up your effective firing range for protected gunner. Makes sense to me.
And now - since a wishlist is open - allow infantry units equipped with underbarrel grenade launchers to fire smoke at longer distance like assault guns
