It's that most of us just don't care, and in fact, in many cases, the outputs of that collected information lead to a more pleasant user experience (auto - scheduling calendar events based on content of emails, Google Now, etc). (theverge.com)
The actual content of the email varies somewhat, but a large number of Google Play Android developers have received phony notifications that their apps are violating Google terms of service. (goodereader.com)
The congrats were both a friendly greeting and a way to lead into the real content of the email while also saying, «I see you there, Kev. (huffingtonpost.com)