When I buy a game, I want to be 100% sure that I will be able to play that game whenever and wherever I choose in the years to come. Ideally that should be out of the box, but if a crack exists for what looks to be the final patched version, then that may suffice. It's hardly an ideal solution though.
Your goal is unattainable for ANY software which means you might as well give up on computers now. A lot of even completely unprotected stuff is just not going to run 5, 10, let alone 20, years from now on Windows SuperDuperWhatever. Even the update to Windows XP (SP1 or SP2, I forget) broke a lot of software (not just games) and made it unusable. I've never gotten some old game software I have (SS1 and MoM for instance) to run on anything other than some old systems that are years dead now. I'd love to play them again but it's just not happening on any system I've tried.