What if Windows 8 was intentionally designed to be the way it was? As in, some user test groups were reported to all have had a negative response to Windows 8's UI, so why would Microsoft not change that before release?
Why? Lighting doesn't strike twice.
Windows 7 is and was Microsoft's fastest and best selling Windows version of all time. That's an accomplishment in itself and something that can't be replicated. vista was such an awful and poorly received OS that left people waiting for a good Windows OS for several years. Once that happened, 7, everyone loved it immediately and switched and upgraded to that.
So back to 8, could it have been intentionally flawed to be warmly received only to give way for Windows 9? We already know Microsoft is going to be actively listen to feedback (remember the "Windows 7 was my idea?") and develop much more features and changes to the OS, both Desktop and modern UI, so that 9 is an awesome OS that will make 8 haters fall in line for 9 and xp holdouts be fine with 9 and mine some 7 marketshare for 9.
Also, it could also reemphasize the "good, bad, good, bad" pattern of Windows releases.