I am very disappointed. I started with Photoshop 5.5 and upgraded to 7, CS, CS2, CS3 and finally CS5. I feel like I have been taken advantage of by Adobe.
I can see how you might feel that way but I'm not sure approach was really optimal. I know some people like to wait a long time before upgrading. There is some logic behind deferring an upgrade a couple of month so that the kinks in a new version is ironed out. However, that approach isn't the best approach from a return on investment basis. To get the best ROI, the best way would be to always upgrade as soon as a new version is available. Then you have the entire life of that version to depreciate the cost of the upgrade.
The question of whether or not to get an actual upgrade is a different matter. You skipped version CS4 and upgraded to CS5 under duress. Can't say I blame you for skipping CS4, but if you are using Photoshop professionally, CS5 had a lot to offer vs. CS3. If you had upgraded to CS5 when it was first released, then you wouldn't be in this pickle.
I will say I think Adobe mishandled the whole 1 version back announcement and extension of the grace period. I think it sucks...but it is what it is, a blunder (and not the first blunder by Adobe over the years). When Adobe changed the "any version to the current version" policy back in the CS or CS2 period, there was some complaining then as well. But not as much as the whole point product vs. suite upgrade policy meaning if you got a suite you had to upgrade the entire suite...
There are business reason why Adobe is trying to transition from a perpetual license to a subscript license and a lot of it has to do with revenue recognition and accounting practices. As it stands, the way Adobe accounts for the cost of the development for an upgrade must be deferred over the entire life of that version and the only changes that can be made are bug fixes and compatibility maintenance updates. The engineers are precluded from adding new features or functions because of accounting (you can blame Enron for that).
Thus major version upgrade end up getting feature lock for usually 2 years, which sucks for the engineers and the users. If Adobe can transition to a subscription basis, new features and functionality could be added at any time so the problems of compacted development schedules would be reduced. Note, I'm not trying to defend Adobe's handling of the 1 version back policy change, I'm just trying to explain why things have come to this.