They want people watch it on BBC America instead of just downloading it.

I also always thought it would be cool to have companions from other planets or other times. That would be harder to write though.

My top wish for the show is that they'd run several series at once. There's no reason the 12th, 20th, and 37th doctors, for example, couldn't have shows running all at the same time. However, I could see it bombing if not done well, plus it commits the writers to certain things. (Though Moffat could get out of any continuity issue I think.)