@eqtwink
It seems to me that your way is the lazy way and the trap. It takes the story out of context and homogenizes the characters. In this story the distinct dialects are particularly needed to emphasize the distinction between the societies and their roots. Your way would end up with all the characters speaking the same way and as a result the important differences between the characters would fall to the background and get lost. In the latest story in particular these differences are the reason for the story.
Not necessarily. It's a safeguard from overwhelming readers with difficult to parse dialects, but it doesn't eliminate having different characters speaking in shorter sentences, or the smart-ass expounding ad-nauseum (remind you of anyone?) All it does is to illustrate how a character's accent sounds, and then rather than continuing to bludgeon readers with these mostly trivial details, you simply remind them of the accent so they don't forget.
Creating distinct characters is hardβbut there's no reason to make it equally difficult on the readers too.
That said, if you've ever read my work, you'll notice that I typically fall into this self-same traps, as most of the characters speak exactly like me. But again, that has nothing to do with their accents, idioms or dialects, it's simply a reflection of how I think and discuss things, so I extend it to my characters.
It's best to separate characters from yourself, but also to separate their personalities from cheap tricks, like odd-ball dialects. Defining characters is more involved than just giving them odd diction.