I worked on SkyDrive/OneDrive for a few years. That's what we thought too. This stuff inevitably starts out with "seriously, how long is it going to take to make essentially a wrapper around rsync" and ends up with "Hey, guess what happens when you cross filesystem errors with distributed systems errors when dealing with unmergeable files?"
This is a deceptively challenging space, particularly if you want to do sharing and group work in a reasonably intuitive way. Which is why Dropbox has managed to remain a company instead of simply being eaten up the first quarter that appl/ms/google decided to get into this business. Note that all three have an offering, and at this point I know that OneDrive is actually pretty good, but for years it was kind of an uphill catchup struggle.