Why? Am I supposed to think that there's something acceptable about punching a man in the face when he's already lying passed out on the floor?
you make a very good point
that's the single thing that has always jarred with me, and i'm a huge fan of mma
a true martial artist might have pulled that last blow as he realised it wasn't necessary, indeed henderson might have against another fighter (although he specialises in that move, but it it does ensure a knockdown becomes a knockout). but there was bad blood between the two, soured over the preceding series where they'd coached opposing teams on tuf reality show
i think it's one of the relics of the sport from the days when it was more brawl than art. as the audience becomes more educated they appreciate a higher level of sportmanship; nate marquois was highly lauded for exactly that in his most recent bout, and it's noticeable how the audience attitude and response to, say a fighter being ground 'n'pounded (that used to get the biggest cheer) to a fighter reversing his position by sweeping his opponent (now that gets the best response) to see that the audience is becoming more educated
but the spectacle of an unconscious person getting lamped is unpleasant, and requires a refinement in the rules.
it's a bit of a tricky one to achieve though. the essence of mma is the combination of striking and grappling, and since most grappling happens on the ground the fight can't be stopped every time a fighter falls, as in boxing. the follow up punch also comes so quickly after the knockdown it's essentially part of the same combination and the fighter will just be following muscle memory, and is often too quick for the ref to intervene
and the striking keeps the grapplers honest on the ground, means that the striker still has a chance when down on the mat. grappler v striker used to be the mainstay of the ufc, and the guy lying on his back often wants to be there as he's hoping to catch an arm and break it