Slate has a great slideshow about the progress of the fight scene. It takes ten scenes from the history of cinema, starting with The Big Country (1958) and ending with Eastern Promises (2007). The gist is that fight scenes are becoming increasingly fast paced and hyper-edited at the expense of spacial clarity and cinematic tradition.
However, I for one vastly prefer some of the more recent scenes to the more traditional examples. The Big Country clip seems like a joke, the few edits feel arbitrary and the wide shots make the action appear insignificant. And I've never been a fan of Oldboy which is too obviously artificial and never really engages me in the action. Meanwhile, The Bourne Ultimatum and Natural Born Killers clips completely enthrall me and are exciting to watch even without the context of the story. That makes me think the progression isn't a bad thing and I wonder if some people's objections to the fight scenes in movies like Batman Begins are the result of a generational difference.
Based on those ten clips, I would say the most important element in a good fight scene is to create a sense of urgency in the viewer and make sure the fight scene is consistently moving (unlike Return of the Dragon or The Big Country, where you are literally seeing the same punch/counterpunch routine as if the fighters are running in place). The Bourne Ultimatum continually raises the stakes faster than you can even keep up with what is going on, and that challenge to the viewer is what keeps it interesting.
A comparison is made to the heavy editing of musicals today (Moulin Rouge!, Chicago) and how the old Fred Astaire movies of yesteryear relied much more on action within the frame and not so many cuts. I would say that movies used to be confined by the amount of editing and number of angles they could get as a result of technical limitations, and that movies used to be much more about spectacle...you could watch Astaire dance in a single shot and be impressed merely by his ability. But these days we are probably quicker to disbelieve what we see...CGI and special effects are so good that we assume what we're seeing is a lie. So maybe fast editing is just a way of staying ahead of our doubts and thereby perpetuating the illusion.