Economics of Middle Earth in An Unexpected Journey

[gdl96]

Anybody with a better grasp of economics want to take a stab at this? Or at least a better understanding of the politics of Middle Earth circa the time of the movie?

I understand why the City of Dale was so prosperous (pre-Smaug) as it was explained in the movie that the economy was driven by a wealth of natural resources and skilled labor. So it made sense that they had a marvelous and advanced capital city. And I guess Rivendell is prosperous because...Elven magic? Actually I'm not sure of that, either. Maybe military expansion and fruits of conquest?

I really wonder, however, why there was such poor infrastructure in the Goblin city in the Misty Mountains? There was surely some sort of mining operation going on, which must have been driving there economy. And they must have been prosperous enough to support what seemed to be a large population of goblins. I understand it was ruled by a despot, but even despots like to build nice things in their name. The entirety of their transportation network was comprised of flimsy rope bridges and hanging platforms!! Is there a good explanation for all of this disfunction? Did the Goblins lack access to contemporary financial innovations that allowed for the funding of more advanced construction techniques present in other Middle Earth cities?

Anyone have any thoughts on this?