I have mentioned this a few times in various threads. However this seems the most likely area to discuss it.
Some liners note Azeroth Music a Division of Blizzard Entertainment.
Even on their website on the left side, the albums are noted to use Azeroth Music
http://us.blizzard.com/en-us/games/music/wow-bc.html
This seems to be for all of their albums that are listed on iTunes.
In my opinion a note or some editing should add that to these entries.