It's not just government snooping, I trust big companies even less.
They will attempt to "monetize" the data in any way they could. And the same data can be stolen, one day. The fact they can give them to governments is just one of the issues.
The main one is they are breaking fundamental human rights behind the "improvements" finger - but it's all about easy money. Great software requires great people and big efforts. Stealing user data, any Zuckerberg, Schmidt or Nadella could do.