That's something I agree on... I liked hearing just British and American accents. I could see a variety of UK accents actually, and even the odd Irish one snuck in like Jabba's that was dubbed over.
The thing is that Lucas is pushing this accent issue, like you said, with it starting iwth the Neimodians.
Those are characters who should've had their own language and freakin' subtitles.
I like Watto, dunno why, but the Neimodians it just doesn't look/sound right together....
Same goes with Dexter Jettster. I don't look at that thing and think of that voice. A surly American accent perhaps, but not what we got.
I'd label Jar Jar as similar, and all Gungans...
Sometimes, Subtitles can really make your characters more "deep".
Chewie never uttered one intelligible word in the whole trilogy, but yet he was such a vastly superior character to many prequal characters that you can understand EVERY word.
If I were to redo the prequals, thse are things I'd have changed up. Tough on Jar Jar to limit him to Subtitles though, unless you actually limit his character as well (not a bad thing though). If you leave him with all his dialogue now though, Subtitles would be distracting. On the Neimodians and Dexter though, it'd be really quite nice actually, what with their limited lines anyway.