Why has no one said for the lure of financial gain? Google isn't going to make many of their new employee’s multi millionaires through stock grants. There are a lot of appealing companies that have an opportunity to make it really big right now and pay off handsomely for those that work for them.
Along the same lines a lot of people at Google have worked “enough” and want to take their money and relax / go do something else. Since many folks there are financial secure it is really up to them when they want to take a break. It seems in the technology space anything beyond about a two year term is considered a long time to work at a company.
Overall I believe Google is still very attractive, however if you want to hit if big financially there are a lot of other places nearly as appealing with that large financial incentive still out there.