Lightsaber duels are obviously primarily about entertaining the audience, and the fact that they swing high and whatnot is because they can't, y'know, actually smack each other in the face. But I do agree that there are some strange techniques that can only be chalked up to Jedi premonition. I also expect it is less about looking for a killing blow and more about being so complicated that you can force an opening. The battle between Anakin and Obi Wan has a section where they both just spin their lightsabers around, standing facing each other, completely ignoring each other for a couple seconds. This looks stupid until you realise that at any moment one might strike from a variety of angles, and the other might also strike, so they must be prepared to defend also.

Swordfighting in any show is incorrect because it was traditionally a much simpler affair. One or two attacks and someone is dead. I read the Wiki entry for stage fighting and yeah it explains why it's a little more showy (and I mean, that's obvious enough, but still).

The most important question is why do Jedi fight at all. My friend had a theory as we were growing up: two Jedi (or a Sith and a Jedi, whatever) should first sit in two armchairs facing each other. They fight in their mind, like that one bit in Hero (iirc). Nothing happens, they just use their foresight to see the outcome. Then, if they are not satisfied, they fight from their chairs, using the Force to throw and catch and deflect and attack using Lightsabers. No physical movement need happen. Then if they can't win I suppose they play rock paper scissors or something. Nobody needs to stab anybody.

My favourite fight is Darth Maul vs anyone because Duel of Fates just the music makes it. Anakin vs Obi Wan was pretty excellent because of the intensity of the actual fighting.