Greg Yardley has a great point, when he says:
It’s just good business sense – if you want to kneecap the market leader, you have to reduce switching costs to zero.
It’s true, in an ideal world, people would agree on a standard set of APIs. And there are certainly people that go that way, and they should be lauded for that. But there will be more folks who don’t. And in that case, we should just clone their APIs.
UPDATE: I heard back from Fraser who liked the idea for FlickrExport, and has posted a ticket