It would stop people who Lay N Pray and don't move on the ground because if they don't move they can poke them and it would stop people holding people against the cage.
Eye pokes are as 'dirty' a tactic as deciding to tweak an opponent's balls or jam a thumb into their windpipe. I'm sure, in someone's backyard, they're doing this & calling it 'backyard wrestling". Go check 'em out & then you & their one-eyed selves can check out UFC on the telly!
Would you fight in a promotion where there was a reasonable change you could finish your fight in the hospital with no eye-sight? No, I don't think you would. I doubt any UFC fighter would like that either. The object of professional MMA is to defeat your opponent, not permanently cripple/maim them.