Letting someone read my mail and track me across the internet is a loss of privacy. There is no need for a breach or erosion of privacy, because by using gmail I'm giving up my privacy in exchange for a free email service. That's simply the deal.
The question is, does this undeniable loss of privacy matter and can we know how great that loss will eventually be? I think it does matter, partly because we cannot know or control the extent of the loss and we cannot easily take it back (if at all).
There's also a great security risk if so much sensitive information is stored in one place. Google is certainly more competent than I am in securing their database. But the incentive for someone to steal it from them is orders of magnitude greater as well.
The question is, does this undeniable loss of privacy matter and can we know how great that loss will eventually be? I think it does matter, partly because we cannot know or control the extent of the loss and we cannot easily take it back (if at all).
There's also a great security risk if so much sensitive information is stored in one place. Google is certainly more competent than I am in securing their database. But the incentive for someone to steal it from them is orders of magnitude greater as well.