This very issue has come up often within my circle of Star Wars buddies. After we saw the saber fight at the end of Ep1, we thought back to EP4 and realized how epic that fight was supposed to be, and how it plays out so anti-climactic now, after seeing how awesome the new saber fights are. It's even worse when you show a friend the OT, and all they've seen is the PT. When it comes time for the saber fights, they usually respond with "That's it?"

But lets be real, the real reason these fights look the way they do is that they are OLD, and expectations were not nearly as high as they are today for that kind of action. Just seeing a lightsaber on the screen was cool enough. But would I want to see it changed? No, probly not. I mean, if the current SE CGI sticks out real bad, imagine how awful a completely digital fight would look in the middle of a 1970's film.

There are many issues like this between the OT and the PT (the ships, the environments, everything pretty much) caused by doing films 20+ years AFTER their originals were released. It's just chalked up to technology, and any attempts to justify the differences is just kinda silly.