I see this as a good thing
Agreed, its too easy to building camp on some maps and any player with half a brain can easily dodge grenades - it just means wasted Muni in the hopes they aren't paying attention.
At most you'll only get a few models but that's fair if you going to be spending 30-45 Muni. I don't think this would be that bad for dodging grenades - its not like HMGs get obliterated right now if they get caught while trying to exit and theoretically you'd only have half your squad in the building as opposed to an entire HMG crew.