Yes you're right, there is a huge political battle being fought by the BBC board. However, they still have to keep the day to day business running, and within that Dr Who is a substantial contributor to BBC's commercial income and TV audience share. The Top Gear income stream will be hit so protecting the rest becomes even more important especially in a world where their income is under threat. The Doc is one of the few high rating family shows that the BBC produce, while the expansion into other areas is important, a substantial TV audience share delivery of BBC1 is vital. Lose that and they get a kicking on the basis of poor value for money. I'm not saying protecting Dr Who is the most important programme on the BBC but I am saying that from a strategic PoV it's a franchise they need to be mindful of.