without reading any other replies yet, maybe the fighters themselves dont like it? I immediately thought of JDM when i saw this. You think that guy would want the spectacle of a big production walk out? I would think most of the roster aren't O'Malley types who want to have all eyes on them. And most aren't JDM who barely gives anything, but there re more like JDM.
Anyway, ive always been fine with the walk outs being a footnote and the production quality of a UFC product gets a litttttle better year by year without radically changing too many things up.
Also i think the UFC would counter this thread with the answer "well we have the pre fight videos" which would be mocked by everyone on here and rightfully so.