I find it extremely irritating when characters constantly pause in the middle of sword fights in order to speak. When characters focus more on speaking than on actually fighting, the duel becomes unrealistic. Anyone in a life-or-death duel who focuses more on speaking than on fighting frankly deserves to die.
Who cares if it’s realistic? It’s about drama and character development. If there’s no interaction between the characters then it’s just a meaningless, dragged out fight.
What’s great about the duels in the OT is that they weren’t just acrobatic fluff. They were about the characters and their conflicts. The talking is necessary because it adds drama.
If you were fighting with someone close to you and there was a lot of history and emotion behind the fight, you bet your ass you would be talking during the fight. It would be weird for them not to talk. Could you imagine if there was no talking at all during the ROTJ duel. You would lose so many great character moments and completely suck the drama out of it.
Character development is more important than flashy spectacle.