I disagree. They tried exactly that with .Mac and MobileMe and failed. The problem is that the proprietary approach that worked so well in case of hardware and software isn't compatible with the web.

I don't know much about iCloud, but I really hope they had learned the lesson and made it more open by providing APIs, allowing data migration, and supporting tools for other platforms. However, this might be just my wishful thinking.

When they launched MobileMe there were no iPads or iPad Touches.

It's a different ballgame now I think.