Don't forget that the majority of people see computers as tools or vehicles, and just like you have to fill your gas tank from time to time with expensive gas, they think it's perfectly normal to pay for software regularly, even when it doesn't offer new features. Just keeping it going costs money. That the upgrade from CS5.5 to CS6 is a 'Critical security vulnerability fix' is a detail most users won't even notice.
That's just like saying you should pay for car repairs when a faulty design of the cruise control made you loose control of it and crash into something.
You just can't make this stuff up! True creativity right there.