Um.... there must be some. I'm not able to think of any...
Okay, here's one: Microsoft wants to make some more money. With effective control of business PCs through its Windows and Office software, they can force users to buy Windows and Office upgrades and new versions.
That's not your computer, it's Microsoft's. If you want to keep using it, pay up!
Don't be getting smug if you own a Mac. That's not your Mac, it's Apple's, and you'll pay more to Apple for a Mac than you will to Microsoft for a PC.