Timstuff said:

Nothing in the OT suggested that green lightsabers were special

I agree, but this isn't my personal reason for wanting green sabers (at least largely) removed from the PT. When we originally saw Luke ignite his saber for the first time in ROTJ, our reaction to having only seen blue before wasn't "it must be a rare crystal" but rather "holy shit, a new colour!"

That moment is lost for new viewers if the PT is full of green sabers.

It's possible to preserve the impact of Luke igniting his saber though, but in a different way. Instead of "holy shit, I've never seen that colour before" it could be "wow, he's got the same colour as dooku, how symbolic".