This discussion seems to have strayed off-topic to purchases which Apple has taken away.
Regarding the OP's topic of actual personal files disappearing, this is STILL an issue eight years later with the latest iTunes for Windows. I have been doing some fairly extensive reorganization of my music library, updating artwork and tags. I've discovered over the past month, several random tracks from various albums have simply disappeared from my library.
When I look in the hard drive folder structure, the files are still there, but sometimes in an older folder or with older artwork and tags. It appears that iTunes occasionally misses a track when updating artwork or tags within albums. Sometimes this is obvious, because iTunes will break out a single track into its own album after a change. But in this situation, tracks appear to have been completely dropped from the .itl library file.
Seeing no simple way of ferreting out the offending tracks, I dragged the entire library folder into iTunes and let it sort through the dupes. This seemed successful, and resulted in about a dozen tracks being reunited with their albums, but it also resulted in several settings being lost, such as "skip when shuffling." A few other tracks that appeared were ones that I had deleted within iTunes, but were still hanging around. It's possible I clicked 'keep files' instead of 'move to recycle bin,' but I have my doubts.
This is a situation which has gone on too long, and it still doesn't explain why occasionally I find an album completely missing both in iTunes and on my hard drive, and I have to resort to digging out my backup drive and re-add it.