This is a good point I think many people are overlooking. (Full disclosure - I work at Google now.) Your project matters too. People working for great managers on things like search algorithms, Android or open source initiatives are much more likely to love their job. People working for managers they hate on things like Orkut, ATS, or cross-browser compatibility testing are much more likely to leave.
In a company as big as Google, different employees can have very different experiences. When you read this group set up for employees who quit, you're seeing the least happy segment of the employee population. I know it doesn't work out for everyone, but I think the average Google employee really likes their job, and I would recommend working there to any programmer who was thinking about it.
Just my 2 cents.