I'm reminded of how Jean-Louis Gassée, head of Apple's Macintosh development in the late 1980s, responded when asked how they plan to connect Macs to the network. He held up a piece of phone wire and said "this is our network". This was a reference to Apple's proprietary LocalTalk protocol which could be used over regular RJ11 connectors.
The gist of this story is that Apple completely ignored the need for interoperability with the Mac. The iCloud has a whiff of the same hubris.