My problem with the Navy's BFG was how it came out of nowhere and fundamentally neutered the badass-ness of Devastator. It feels like there wasn't any foresight on Bay's part for how he was going to deal with Devastator. He was spending all this time setting up Devastator as this unstoppable, crazy huge, uber-destructive monster, and when the time came to "dispatch" Devs, nobody could figure out an intelligent way to get one of the bots to do it, so Bay just said "Eh, why don't we just have the Military blow it up? Just have Simmons say 'Thank God you have this super-secret, monster-killing gun conveniently located within shooting distance of this monster.' And then they kill it." Maybe that's my beef with the military portrayal, especially in TF2. The Autobots can't figure out what to do, and can't beat the bad guys, so the screenwriters just have the military drop a MOAB on everything and it fixes the problem.