I cringed when TB said that an RMAH system would actually be better suited for WoW.
RMAH would absolutely destroy WoW.
At least in D3 I can choose who I play with. WoW on the other hand is a persistent world where I'm playing with thousands of other people. Those points have already been covered so I won't bother to retype it: http://forums.battle.net/thread.html?topicId=27822642364&pageNo=1&sid=3000#1.
TB seems like a great guy and I enjoy his commentaries, but it seems to me he's misunderstanding something if he thinks RMAH would fit better with WoW's playstyle.