I asked the same question to my CO in 2008, SuperBoy. He wasn't even sure why it wasn't on JW.org, but you could still order them from the literature counter. I do not know if that is the case today, but if you are still in try asking them if they can order it.
The only reason I could see them not being on the website is due to a copyright claim that a song was plagiarized or that a song sounded too similar to a non-JW song.