A person might feel justified for downloading a copy from TPB or wherever being that they had legitimately purchased 6 original versions previously over a 30 + year period.
Although over those 30 years, back up copies could have been made on 2 occasions mitigating 3 of those purchases and also preventing them having to make an mp3 purchase.
Vinyl (purchase 1)
Vinyl replacement (due to wearing. purchase 2)
Tape purchase (depending on circumstances, this could have been backed up from vinyl if you owned a cassette deck)
Tape replacement (use back up)
CD purchase (purchase 3)
CD purchase replacement (use CD back up)
MP3 purchase (use CD back up)
My view is that you should buy the MP3 versions for $10 and make a back up
Media devices are going to change and provided they continue to use a common software, then with this purchase (and the myriad of cost effective storage devices) you should be ensured an excellent copy and interchangeable back up for years.
I simply don't feel that a person should be able to download copies of all media they have ever purchased simply due to format and /or device changes (which are optional). Just because a new device allows portable listening for example (such as an mp3 player) and you bought a record 30 years ago, I don't believe in those scenarios it justifies downloading a copy.
Same for loss of media or media transport malfunction.