Buying OS3.1 for an A2000 didn't mean you could just move it over to an A3000 either. A500 version didnt' work on an OS3.0 A4000. A4000 didnt' work on A1200. Because of the diffrent ROM chips and what they needed to do.
The situation isn't quite the same anymore. But it's their product to sell, their choice how to sell it. If you want to try and do something different than the thing you bought intended, if your local laws allow then go tinkering to make things work.
