I really hate this business model. It's one thing charging a subscription for all the latest shiny new features, but what usually ends up happening is that you are forced to upgrade because there is zero file compatibility between versions *cough*Autodesk*cough*, which is just not acceptable.
Someone who is content with the feature set of an older version should not be forced to buy a new version just so they can still open files from other people.
I guess the problem here is overall lack of backward compatibility in many software for example Adobe's Flash with only one version backward, which is stupid when you want to do trivial things without using newest features.