I thought the same thing years ago when MS first made the announcement. But then I realized that none of the MS OEMs were building equipment to compete with Apple. MS wanted to build the OS and User experience - but nobody was building an "iPad" or "MacBook Air"
Now folks are talking about the Surface & Surface Pro and stating how Apple and others are beginning to imitate MS. MS may have actually gotten this form factor right. But they had to push the Innovation and not rely upon OEMS to invest in this space.
Imagine the conversation: "Dear Dell/HP - we know PC sales are falling. Please spend money in this risky area and build a decent future tablet/laptop thingy" MS had, up to this point, been placing its hope for hw in the hands of others. With consumers flocking to Apple in this "new" mobile space MS had to stop it. But the OEMs were trying their own things to combat market slide. OEMs and MS were competitors - they wanted more features in Windows too (HP went to Linux for awhile).
I believe this was a good plan for MS - own the direction and put their money where their mouth was. Still plenty of work to do - but now I think more people are starting to consider Windows Hardware again. Apple is building a Pro tablet, and OEMs are jumping in too.