Agree with the first paragraph, they'd rather cut just about anyone than pay more than they want to. If you're decent and you'll stand and bang like that Diego Sanchez vs Gilbert Melendez fight then they'll pay up, at least they did with Melendez (though I think the UFC regretted that contact as GM went from contender to also ran very quickly after that fight). But who knows, maybe they feel like they have enough guys willing to bleed in the wings now and wouldn't be swayed now in a similar situation.
I do see a solution, though, which is Bellator, or eventually someone else, agrees to pay fighters the 50% cut instead of 33% and the UFC have to match our lose most of their best guys. But, Bellator probably like these suppressed wages too, they've never tried to out spend the UFC even though their parent company could do it if they wanted.
But maybe someone else, maybe a league started by fighters or investors who are fans, who care more about a good product than profits? Hell, some jaded rich person might take the high road on fighter pay just for the PR points and internet love, as free advertisement for this other league. Worth paying a bigger cut it out gets you on top when you weren't.