This is more a general comment than one aimed at The Office specifically, but I'm of the firm belief that American TV stations frequently make a big mistake in making American versions of British comedies, wrongly believing their audiences to be too stupid to 'get' British humour.
Yes, there is a difference between British and American humour, but I'm sure that an American audience, knowing a comedy show to be British, would be able to "tune their brains in" to our style of humour to be able to cope. After all, we don't often remake American shows (anyone remember The Brighton Belles?), but simply import them as they are. There may be the occasional reference we don't understand, but on the whole we laugh at The Simpsons, Frasier, Will & Grace, Scrubs etc because we're able to appreciate them as they are.
When the TV companies try and Anglicise an American comedy (or Americanise a British one), they produce an uncomfortable hybrid - one nation's actors trying to do the other nation's humour, and - quelle surprise - it doesn't work.
Coo, don't I go on once I get started? : -)