This is less about how the visuals were achieved, but about the lack of passion put into them.

Think of how awesome the following should have looked

A guy fighting with two lightsabers at once.
A lightsaber duel in the dark.
A guy fighting a four-armed monster each arm wielding a lightsaber.

The lightsabers in the dark I fantasized about in the 80s. When I was in middle-school I made an art project called "Jedi Fighting In a Cave" with a piece of black construction paper, whiteout, and highlighter pens.

Yet all three ammount to nothing. Nothing memorable or exciting. They all last for less than ten seconds.

I think the commentary on the ROTS DVD said that they couldn't figure out how to do a four-armed sword fight, resulting in Grievous losing two arms in 9 seconds.

Ray Harryhausen did in with STOP MOTION in 1973!!!

What should have been these extremely fun and visual fights almost result in just a throwaway joke.