if it was part of the tcn, yes, then it would be green grey. the concordia carrier, which is also in the game, is just that.
the destroyer, however, is for the terran militia, hence the blue/grey color scheme
actually, you can see the concoria's bow on the first pic
nexus does have a minimal fisheye effect, but that's minimal.
the other ships are indeed quite far away.
if you check the shipyard thread, it gives you a failry good idea of the size of the destroyer compared to a bengal.
also i have to say that according to all sources i could find, this destroyer type is way larger than the exeter or gilgamesh