I just hope they use more than one voice-actor per race, it is sort of unnerving knowing that all the people of one race have the exact same vocal cords with rare exceptions.
I have to agree on that. Every character of the same race having the exact same voice might have worked in Morrowind because you only had to listen to it in generic greetings and combat taunts. But if Bethesda is going to keep using fully voiced dialog (Which I am almost 100% certain they will.) they need a bit more variety. Obviously, I know there's no way they can give EVERY character a unique voice, even games where there is a fairly small cast of named characters still tend to give generic nameless people a few generic voices, but they can at least do better than Oblivion, maybe if they'd spend their voice acting budget on hiring a few more voice actors for characters who you'll be speaking to throughout the game instead of getting famous actors to voice characters who are going to die less than 30 minutes into the game...
But Morrowind seemed to have the right general feel for each race. But as far as real world accepts goes, it's important to remember that Tamriel ISN'T the real world, so it won't necessarily have the same accents as real life, the characters in the game probably aren't even really speaking English, it's just rendered as such so players can understand it, and since the voice actors probably will have a hard time doing fictional accents without sounding forced, they can instead go with real life accents that fit the characters. Rendering the "standard" accept (Which presumably would be what Imperials usually speak with.) as American sounds alright to me, as Bethesda is an American company, and would presumably aim to appeal to American audiences first if they had to target one country over any other, an American accept would be most familiar to American audiences, so it would seem to make sense that the accent that is meant to be the "standard" be rendered as an American accent. With that in mind, characters from other races could perhaps speak with an accent based off whatever real life culture they're inspired by, though I think it would be better to just go with whatever sounds "right" for them, because just because a fictional race has some aspects resembling a real life culture doesn't mean their accept must be the same.