Why?
Other than rank 5000 MG42 spamming Ostheer players no one wants to have stuff like concrete bunkers in the game.
It's not fun at all and I am glad the current ones are not used.
while i mostly agree, i think you underestimate the fact that the majority of the playerbase enjoys a rather different play style than you and i would (i.e. tower defense) and indeed wants things like near indestructibe bunkers and omnipotent emplacements, allowing them fend off endless waves of flesh and metal with minimal imput.
clearly no fun to play against, but i guess you'd have to be on the receiving end playing allies at least once in a while in order to be able to relate.
that being said, bunkers and other emplacements shouldn't be patched out of relevance either imho, so the slight price decrease or added utility would be a good move in my view. still, a big no to any increase in durability, be it more hp or less damage by at guns as proposed above - they're already tough enough for what they're supposed to do.