There is a lot of missing the point on this thread. This problem goes down to the core of the social and psychological problems and tradeoffs that happen in GUI and application design, web design, and any other system that is accessed by members of the general public.
Somewhere there is a manager yelling at a designer because "it's hard to use" because there were complaints from users that they "just put in there password" and "why should I do that again?" when they were making a series of purchases. So the designer incorporated a 30 minute time out or grace period to get around the whining. Sometimes there is no absolute sweet spot... there is going to be whining about the design either way. They probably should incorporate a variable (as someone else on this thread mentioned) so the user has control and Google can say that the user has the power to make a choice.
People are thinking this is deliberate by Google? Bah. Google isn't 100% non-evil, but I don't buy that. They still aren't doing their design in like Microsoft does, in their Marketing department.