I have to give the folks at Flickr credit for their competitor API position. I have been in heated discussions dealing with the openness of systems. In my experience there exists a group of people that fear losing something (Take your pick: money, customers, advantage, IP etc..) because of being open. My response to that group of people is that which you fear losing was never yours to lose.
In Flickr’s case, the images, tags, relationships, and comments are simply on loan from their customers. Flickr’s willingness to respect the customers ownership over those attention artifacts is only going to strengthen their position.
Additionally, I think the quid pro quo approach by Flickr is reasonable but not necessary. I subscribe to the belief that attention is symmetrical. Flickr by paying attention to their customers needs will only receive more attention from their customers, resulting in less attention for their competitors.