Sorry, this is longer than I thought it would be. Bear with me...

At some point iTunes "upgraded" to include artist avatars that you couldn't switch off or choose your own images for. Anyone it couldn't find had a placeholder grey microphone icon, which was bad enough. If you had some obscure artist that happened to share a band name with a more popular act, it would default to their image. Unforgivable.

It pissed me off enough to seek another option and I eventually settled on Foobar2000, which was everything I had loved about Winamp and OG iTunes in one. Also, fully customisable, albeit with a learning curve. Moving everything into Foobar, I realised I needed to redownload all album cover art, for my 40,000+ song collection, in as high a resolution as possible (discovering albumartexchange, and Advanced Google Image Search, in the process).

Halfway through this task, I realised I should probably also redownload anything I had that was less than 192k bitrate, and maybe in some cases I should go flac, just to "make sure". Fast forward a year and I have about 70,000 songs, mostly meeting those requirements, and mostly totally replacing the collection i had been building since 2001. God bless Soulseek and RuTracker.

Now, in answer to your actual question, on this journey I found (or, rather, didn't) a whole bunch of stuff that I have from the early 2000s which doesn't seem to exist online, anymore, or only does in poorer quality than I already had it, most of it old UK HipHop from that time. It was a real validation of one of the most important reasons for piracy, though I can't claim it as the reason for my original (or ongoing) obsession!