I guess that's true... but have you never done literally anything wrong? Have you ever downloaded a song or a movie without paying for it? Did you download images from The Fappening? Did you read confidential documents released by Wikileaks? Did you ever watch copyrighted material on youtube?
Congratulations, you've just triggered probable cause. Privacy concerns aren't about what they are doing now, it's about what they are able to do in the future. Look at SOPA, CIPA, and PIPA. The US Congress keeps bring it up for a vote two or three times a year. It only has to get through one time and then it's in forever, just like the PATRIOT act.
Let's assume for the sake of discussion that someday one of these laws is going to be passed. These laws move the responsibility of protecting copyrighted content from the copyright holder onto the Internet hosting companies. These laws turn a civil dispute into a criminal act. They are laws that force ISPs and website hosts to actively police content and report violations to law enforcement. Do you think Microsoft, a $400bn company with government contracts, is going to exercise civil disobedience? Hell no. They're going to throw you under the bus.
Not afraid of private data being stolen? Microsoft had the source code to Windows 2000 and NT stolen. And of course we all remember The Fappening. Storing lots of data in one location makes the target appealing to hackers and worth the effort to crack. Are you comfortable with the idea of your family and coworkers knowing everything you do on your computer?
As Joe Rogan's character said on News Radio, data on the internet is like pee in the pool. Once it's in there you can never get it out again.