If I'm having a lot fun with AmigaOS 4.1 - which I do - then I'm quite happy to pay 30 EUR for an update once a year if that's what they want. On a subscription model, when the subscription ends, you lose the use of the program. That is not the case here, so it is not a subscription model.
If we want Hyperion to continue making an OS for us to enjoy, then we as users have to be willing to stump up a bit of cash every now and again. Principles aside, that's just the reality of the situation. They have bills to pay and mouths to feed, just as we do.
I really don't see 30 Euros as being so much to get uppity about, and I think many of us more than get our money's worth out of it.