Software, especially software from Adobe, is expensive. Just Photoshop is $199 and even the cheapest edition of the Creative Suite is over a grand. It’s a lot to shell out for a pro and a cost that’s hard to justify for a hobbyist.
Adobe has a history of treating their return customers nicely though. If you own an Adobe program that was released within the last three versions, you qualify for a nice discount. If you own Photoshop CS2, for example, you get around $400 off of the CS5.5 Design Standard bundle.
Starting with CS6 though, the company is changing its policy. The only way you can get a discount is by owning the previous version. CS5 owners will qualify for a cheaper CS6 while everyone else has to pay full price.
It seems likely that this move is to steer customers away from the traditional software buying model and get them more eager to adopt Adobe’s new subscription plans.