If you legally own a copy of a piece of software, and the media it came on dies for some reason, what the hell is the problem with replacing that media with a copy from someone else? Has the company who produced the media promised you a long-long guarantee that it will produce you another set if that set dies?
What about years ago when the shop my dad bought my first Amiga from, when the Workbench disks died, we were given free copies of them? Ok, so they didn't have pretty labels on, and if the shop wanted to, they could charge us for their time and materials used.
To me, what you're saying is tantamount to "you're not allowed to perform maintenance on what you bought from a company".
Ehm... Mikey... Would you send me a registered copy of Quake or Napalm CD's if I told you mine was broken and I'd accidently lost my originals?
What if the guy here asked for OS3.9 would you send him a free copy?
If your answer is yes, then I have a long list of things I want you to send me, if it's legal as you say...
:-) See my point?
But I do see your point in -What I buy once belongs to me always- comment, and yes WB comes along with the Amiga Computer itself, but in my opinion you should backup your stuff before this kind of stuff happens...