BBC are out to get what is best for BBC. It's why you need to look at various sources to look at the big picture.
What is best for the BBC is to maintain their hard won reputation for impartiality. They don't have to answer to proprietors with axes to grind, and although successive governments do try and lean on them, history suggests they have an excellent record of resisting such pressure. Their responsibility is to the British public (this is after all public service broadcasting we are talking about) and they have by and large fulfilled that responsibilty to the highest standards.