For a long time now the BBC has been moving from content creator, to being a commissioner of content. This coincides with the lowering of costs in producing that content, with the growing army of people now able to collaborate independently of the BBC in producing content.
I have no idea what the contract between say Hat Trick Productions and the BBC says about content ownership, but it seems obvious to an outsider that as time goes on the BBC will have fewer and fewer rights when it comes to the content it broadcasts. It may be an anathema to BBC employees that they are to be managers rather than creators, but surely that is the future.