I think it was changed for legal reasons though, because no screen credit was given to the composers of the original show theme, and that's a matter that can also intrude even when the production company is the same.
This is great news beacuse it means that Fox hasn't totally given up on the MTM catalog after all (but why couldn't they at least give us Season 2 of Mary first??). Speaking of the last episode of "Newhart", with it's classic twist ending, if that ever makes it to DVD, that is an episode...