No one is "forced" to move to PS. If you are using so much memory or CPU that your processes are negatively impacting other users on the server, you will have to do something - whether you move to PS, or a dedicated server somewhere. or whatever. is up to you.
Yeah, I know ... I read all about it, and your perception of it, over on WHT. Meh.
I think DreamHost has been amazingly patient with you; most hosts would have already told you to take your business elsewhere if you persist in running your site(s) that are causing problems for other users on a shared server.
You should re-evaluate your business model, and what you expect to pay for hosting that stuff, and then make a business decision that makes sense for you. DreamHost is not the proper host for everybody and every kind of site, and DreamHost has told you (now they have told you repeatedly) that a PS is what your site demands ... if you don't want to do that, or believe them, or whatever, then it is probably time for you to move on. You may qualify for a refund if you are under 97 days. You may not be depending upon how you paid.