The way I see it, it's different to compare the TUF fights with no commentary to a live fight. With the live fight, as well as hearing the corner, ref, etc when commentary is off you also get to hear the crowd, which can make a fight either more exciting or boring depending on how involved they are in it.
With commentary, even if nothing is going on in the fight the commentators jobs are to keep you involved in the fight. Can you imagine watching the Gabe Gonzaga and Kevin Jordan fight with no commentary. I think I would shoot myself.
In an exciting fight, it would be nice for the commentators to put down the mics for a couple seconds and just let you hear the fight and the fans, but to always have no commentary would definitely be a mistake.