iTunes may show a screen asking you to Scan for Music or Go to the iTunes Store before your library has loaded. You should see all of your music that’s available on iTunes in the Cloud on the Library: Music page. Start by logging in to iTunes from the Account: Login menu.However, there is still a way you can download everything in one go from within your iTunes Music Library. This page is now entirely useless when it comes to redownload your previous purchases. It is also less expensive generally than the files on the iTunes store.You used to be able to go into the iTunes Store and easily redownload everything from the My Purchases page. iTunes store is like a last resort, I prefer to use sites like Bandcamp where there is no DRM, more options for file formats, and an easier way to download past purchases. *I mean purchasing albums is worth it, not necessarily buying songs on iTunes. And this is a pretty acclaimed album by a well-known artist. For example, using Apple Music with my dad the other day, I wanted to hear 16 Horsepower's last album Folklore, but presumably since it came out on a small record label that is now inactive, it's just not available to stream.

As you noted there are bootlegs and live albums, but there are also many albums that are just not available on streaming for other reasons. Switching from streaming to a fully local library also expands your options. Whether or not it works out to less money spent depends on your situation, but personally I try to buy new albums to support active artists where I can, so I was still purchasing some albums while paying for streaming. Earlier this year I stopped paying for streaming and switched to just purchasing new albums that interested me and I don't regret it. I think it is worth it* and doesn't prevent trying new music or 'expanding your taste' either.

Purchase songs on itunes