Of course I would like to be able to install my keyfile for all my computers too, but if you think it realistic, what would be the better licence scheme for both user and developers on current market situation? I think it's fair compromise currently.
If you could use bought keyfile without limits, that would crash the already small sales to bottom because of the illegal copying, that's for sure.
Any kind of network authentication would be doomed too. I trust my equipment lasts longer than any support services would probably be online in the future. I want to be sure I can reinstall my system in any situation in any time, even when the OS development has stopped. Just like with my old Amiga software.
And as said, you can sell your old keyfile with your old computer, if you want to part with it. In the most cases you have been using the system long enough to make it worth it even if you wouldn't get money back with selling. Compare it to other regular or annual expenses and it doesn't make that much. I bet you can get much more fun with it that many other activities you might be putting your money in.
Mainstream systems can afford for piracy, because of big userbase, but there are some licences tied to hw too.
In practise, OS4 is tied to HW too. You cannot buy new HW without the OS included and charged. And it has separate versions for each platform. If you want to upgrade from your old A1 to SAM or Peg2 or something else, you have to buy new copy of the OS. In practise the same thing like with MorphOS. It just isn't seemingly tied that tight to HW, which is possible because they don't have any support for mainstream HW and thus the piracy isn't such a problem.
I still own my Pegasos1, which has paid OS. And I still own my A1200, which has paid OS too (actually several). Even though I'm currently using Mac mini, I don't see any problem having bought software for those older computers in the past.