I think the fence/cage is about the only thing that is left for the UFC to recreate an environment of "real fighting." Unless you're fighting in an open field without any physical obstacles, getting crowded into/crowding your opponent into something is a viable tactic in fighting. In a real fight, if you have your back against a wall, table, desk, car (etc), you're at a distinct disadvantage. Everyone who ends up in the UFC knows that it's there, so why not train for it?
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto