If Lucas created the sith eyes in the PT as a visual indicator that replaces the need for actual story telling and character development then thats obviously not good. But if we assume that Luke's step towards the Dark side is portrayed well enough, then the eyes would not we for that reason, they would simply be an extra visual aid.

That said I would hate this change to be made because in the OT they were a part of Palpatine's look, not a sith look. I'll be damned if George made Palpatine's eyes that colour because Palpatine was a sith. It was because he was meant to look creepy, nothing more. By making all sith have the same characteristics and looks it just makes everything look smaller and lazier. In the OT lightning was a Palpatine feature, just like the eyes. A red lightsaber was Vader's thing. In the PT red lightsabers, yellow eyes, and lightning are all just sith things so they no longer add anything to the individual characters.