Why Moria?

[CSteefel]

Originally Posted by goldfinger

At the end of the Battle of Aznulbizar, Dain Ironfoot looked into the gates of Khazad Dum and saw the Balrog still lingered and would not permit his people to enter to reclaim Moria.

I don't read it this way. I interpret what Dain experienced as more of a sense of great evil within the Gates of Moria, similar perhaps to what Aragorn sensed when he passed into Moria. I don't think that Dain actually saw the Balrog, or even knew that there was one there. The Balrog may not even have been the only foul thing in the depths--another could have been the Kraken that guarded the western entrance to Moria (presumably this came out of the depths of Moria).

I think the best interpretation would be that the Wise knew that there was some great evil in Moria, Durin's Bane presumably, whatever it was. Not knowing what was there, Gandalf could not judge whether he would be equal to the task or not. Certainly Galadriel and Celeborn did not know that there was a Balrog there.

Otherwise, the northern route seems a possibility, but this is a choice made with hindsight. Initially there was even a chance of passing through Dunland until the Fellowship found out that Saruman was watching that route. The route over Caradhras would normally have worked, except for the apparent intervention again of Saruman. Going back to the northern route after the failure of these two possibilities would have meant a long trek back north, and then following a route that was virtually guaranteed to be watched by Sauron's servants. Merely because others passed that way earlier (for that matter, Elrohir and Elladan had passed over the Redhorn Pass) does not mean that the Fellowship bearing the Ring would have had the same results.