The link in #2 makes for interesting reading.
The issue is with the extensive and long-term data collection/storage....where eventually a person's total identity and history will emerge. All that's needed is a search/correlation 'engine' to pinpoint an individual....and I'm fairly sure Google can dig one of those up.
A corporate [private] global database ...... gleaned by 'overt subterfuge' aka 'the blissfully ignorant' ...... pretty neat, really...as IF they make Gmail 'indespensible' everyone will be obliged to interact with gmail accounts...either having them or responding to them..... and it's just SOOO much more than what a local ISP can do.....they aren't reaching out globally.
For this to succeed Gmail 'needs' to be as big/universal/popular as possible...so sitting in a corner and waiting for customers won't work....critical mass won't be reached. What's needed is a self-seeding marketing strategy...where it's 'pyramid' in nature.....oh, yes...they did that.
Most importantly....reassure your new 'flock' as often as necessary that you are not 'evil' and all is above board..... keeps them happy and contented .... fattening quietly in the fields....
Yes, it's simple commercialism .... proffiteering through commodity generation/marketing .... but the 'commodity' is information.....personal information.
Yes, that's just like your frequent fliers points on your credit card... and other data collections, etc...
But it's one HECK OF A LOT bigger....and potentially far more dangerous.
It's all about "power corrupts ... and absolute power corrupts - absolutely"....
And...
"Knowledge is power".