Originally Posted by Mr. Dent
I've never really heard him speak in any other voice much less a British accent.
Nobody said that MCU Rocket is going to have a British accent. He has one in MVC and in an episode of AEMH, but that hardly constitutes an accent that's set in stone.
When it comes right down to it, a raccoon with an American accent --- specifically a SOUTHERN American accent --- makes far more sense than any other. Since, you know, this is where raccoons are actually from. Not that an "accent" of any sort for an alien being makes sense, mind you, but if you're going to arbitrarily assign a regional brogue, you should make it at least fit the animal's natural habitat.