Google currently has more money than God, which alleviates much cultural pressure to extract marginal revenue from, eg, employees' toy mobile apps.

It could just be the people that google attracts ? People who are constantly tinkering ... side or hobby projects could well be ingrained in the company culture ....

According to the comments in this thread google expects you to notify them when you hack on things off the job, and feels entitled to deny you those activities. Sounds quite hostile towards creative people. Nightmarish, even.