So people don't want to associate the races in TES with certain cultures/nationalities yet everyone is fine with NPCs having American and British accents and mannerisms?
In the English versions, yes, although I wouldn't say Nords in Morrowind, Sheogorath in Shivering Isles, or Argonians//Khajiit, in general, have very American or British accents. Anyway, I'm sure if you're playing the game in French, you'll hear French accents, if you play it in German, you'll hear German accents, and the same would likely go for all other regionalized versions of the games, and that's mostly okay, in my opinion, for the reasons others have posted with those accents being the default accents of the regions most of us, if not all of us, playing these games live in. However, mannerisms aren't all American or British, either. The average American doesn't act as many Orcs I've come across do. I don't know about everyone else, but "Get lost or I'll pull your arm off" isn't a very typical greeting, where I live.