Adobe couldn't get most people to upgrade as fast as Adobe wanted people to send in more money.
The new system is working for Adobe; They are posting record earnings since starting the rent to rent system.
I edit video on Premiere Pro CS4, and After effects CS4. I edit stills with Photoshop CS6 and would be just about as happy with CS4. I edit audio with Audition 3 and would be just as happy with 1. I use Dreamweaver CS4... I can't imagine how it is different from CS1. I used to work with Flash a bunch... but I decided it was a waste of time somewhere around CS2... but I have a CS4 license. I've never used On Location, but I have a license. I have licenses to a bunch of their other stuff too. I used Encore for a while but DVDs are off the back these days.
I ended up feeling foolish most of the time that I upgraded my production bundle licenses and the last thing I did was buy individual product licenses so that I could stay flexible as long as possible.
$600/year is nothing compared to rent or utilities, but when I figured out I wasn't going to appreciate any real value in having constantly up to date software I figured out that I didn't have to spend $600 just yet.
I know guys that are still making real good money on Final Cut pro 7.0.3.
I drive a 2003 Honda Odyssey Van that was paid up 8 years ago. Money in the bank!