i know this post is over a year old, but in regards to what playlists are used for (since none touched on this)... answer: they are used typically to play your favorite songs in your entire library or a select genre/artist/album/etc..., i use playlists for playing my favorite songs from a certain TV show and to listen to my favorites from my entire library and a certain genre etc... Typically i only listen to playlists because as with soundtracks there are usually some good songs in an album but then there are those wacky, off the wall, sometimes terrible songs, or just songs you just don't want to listen to in the one album that if you just listen to the entire album the songs you don't want to listen to pop up, you have to skip them every time, and if you want to listen to more from the same TV show (IE. season 1, season 2, season 3, etc...) without having to stop playing the one album and move on to the next manually you create a playlist for those albums. If you have like thousands of songs (which i do) in your library and you don't want to have to continually be pressing the skip button every time a song you don't want to listen to plays which if you play entire library that is definitely going to happen and sometimes it could take like 30-50 skips just to get to a song you like. Playlists also make it easy to play your favorite songs without having to look down at your phone when a song you do not want to listen to very often, this is especially helpful when you are driving.
