You're both wrong and correct. While the MYTHOLOGY of WOLTK was taken from Norse mythology, the look of the zone and some of the quests (taking out the Ocular, for example) do have some elements of LOTR. Blizz is known for its various pop culture references, so I don't know what makes you think that it can't be an awesome mixture of both.
P.S. For those of you who'll reply "But Mordor had volcanoess!!!!1one!!" I mean the element of darkness, architecture of the buildings, etc. I mean, of course Blizz would adapt the idea to fit their needs by making it icy!