Microsoft's whole disaster with Windows 8 reminds me of a similar boondoggle from the military-industrial complex back in the '50s and '60s. For some reason, the US military wanted to replace their submachine guns, battle rifles, light machine guns, and marksman rifles with a single standard service rifle. That rifle was the M14, which was too big to be a submachine gun, too overpowered for a battle rifle, and had too small a magazine to work as a light machine gun. The Pentagon learned the hard way that you need different weapons for those different roles, and so they switched to the M16 as a battle rifle (which had its own problems initially, but which were soon worked out), the M4 as a smaller, lighter carbine (submachine guns being obsolete as military weapons by then), and the M240 and M249 as light machine guns. The M14 was kept around only for the one role it excelled at -- a designated marksman rifle.
Today, you've got a similar situation with the Joint Strike Fighter program, an attempt to design one fighter jet for the Air Force, the Navy, and the Marines. The Air Force needs a jet that can take off from land-based runways, the Navy needs one that can be launched from and land on carriers, and finally, the Marines need a VTOL jump jet to replace their aging Harrier fleet. A single aircraft design had to take all of those needs into account, and the result is the F-35 Lightning II, which is, by all accounts, an utter dog of an aircraft that's badly outclassed by comparable Russian Sukhoi fighters.
Microsoft is in the same trap that the Pentagon was in with the M14 and the JSF. Say what you will about Apple being the trend-focused "hipster" computer company, but they're smart enough to realize that desktops and laptops need a completely different operating system from smartphones and tablets. Even as they've been earning (much-deserved) mockery for their iDevices, they've also been quietly upgrading OS X for over a decade now, doggedly holding onto their version of the Start button, the menu bar. The new iMacs may look sleek and modern, but they maintain continuity with the old UI and software so that longtime users don't have to relearn everything. They love their flashy gadgetry, but they also know that there's a time and a place for it. Someone high up at Microsoft, on the other hand, seems to have played a bit too much Mass Effect or seen Minority Report one too many times, to the point of risking Windows' status as the OS of choice for business and government in order to push technology for technology's sake, regardless of how it actually works. They think that touchscreens are the future, even though there are many cases where the traditional mouse and keyboard is still superior, and so they load down Windows desktops and the Xbox One with useless bloatware in the name of tech fetishism.