1. the refs should be able to look at the replay (atleast on the big screen) while the fighter recuperates and then make the call. I think i've seen some refs already do this kind of thing
2. if a fighter did this he would have to face the onslaght of the MMA community cause on the replay everybody woulsd see that he was faking
Instant replay is another completely different argument now that you want to be included, and it isn't always conclusive either. Look at football. It can be replayed 50 times and the call is still very inconclusive, so they have to have a rule which says "you need evidence to overturn the decision on the field".
From 1 angle, it could very well look like the guy got a finger to the eye, but from another angle, you might see that he didn't. What if there isn't an angle on the inside because they are close up against the cage? That is where most "flops" would happen. Ref on right side, punch to the left side, opponent says he got a thumb to the eye. Instant replay wouldn't be able to catch that clear enough to help the ref.
So then, you would have more refs NOT calling it, because of the instant point reduction, and people could be more likely to get away with a real eye poke, and the opponent wouldn't get any time to recover. And because there is no definitive replay, fans are torn about who is telling the truth.
In the middle of a fight, you can't blame a fighter for thinking he got poked in the eye when he is getting punched in the head. There is obvious faking/diving, but eventually guys would become pros at it and you wouldn't be able to tell the difference.
"I felt a sharp stabbing pain in my eye, and it went blurry, it felt like I got poked, so I motioned to the ref."
Are you going to tell him he DIDN'T feel that as he was getting punched in the head?