It's a tough call to me. If someone spit in my face my first reaction would be to punch back.
I agree the NFL fines people more money for things that seem like they lack common sense. Like fining Jake Plummer for wanting to wear Pat Tillman's number on his shoes.
But if you were to say suspend Michael Pittman one game for punching Sean Taylor after Taylor spat on him or say kick him out of that game for punching. I think you would be inviting more trouble. I could send in a 4th string player to go spit on the other team's star player hoping both get kicked out, and so what, I lose a player who won't see action anyway and the other team loses a vital part of their team.
I think it was OK they didn't fine or suspend the puncher. Now players know if they spit in someone's face not only will they be kicked out of the game and fined, but they also might get punched on without any repercussion to the person spat on.
If anything Taylor should be fined for lying right to Joe Gibb's face when he told him, he didn't spit at all. The new video they played yesterday clearly shows him spitting.
Taylor should consider himself lucky he is so talented a player. So he will continue to get chance after chance after chance no matter how much of a jerk he is on or off the field. It's the same in every sport if your talented you get numerous opportunities. You have to be a super jerk to mess it up. See Maurice Clarett or Marcus Vick.