Facebook and Google don't log all of my keystrokes across my entire operating system. As far as I know, Google doesn't even log keystrokes within the browser.
If you use Windows, I don't think it's reasonable to assume that Microsoft is downloading your browsing history and keystrokes.
Microsoft isn't doing this either, they are monitoring your usage of Cortana/System Search and your selection of its suggestions (just like Google does for Google Now,) to improve their algorithms. This is really being blown of proportion. Reminds me of people freaking out about Palladium with Project Longhorn.
No matter how you look at it, essentially reserving the right to install a key logger on your computer is unprecedented.