> In the Ultima online case the skins were just worth essentially vendor cash, but without that market force in the middle, the economy tanked. Now if vendors paid less and less for hides as the rate of hides redeemed for cash increased, it would provide a natural limiter on the value of that activity.

I don't think players were killing the animals for the skins, I think they just indiscriminately mowed over everything for skill gain or just to kill stuff.