In defense of the prequel CGI, the actual practical creatures on Ep. 1 were pretty terrible. Look at that dealer in Mos Espa who shouts at Jar Jar or any of the Nimodians.

This probably means that the creature shop they had for Ep. 1 just didn't have the talent of the guys from 1982-83 on Jedi.

However the creature CGI is pretty solid in ep. 1. Sebulba looks fantastic and still holds up today.

Also consider Matte Paintings vs CGI digital painting. Only the best Matte Paintings can hold up on screen for more than a few seconds (the warehouse in Raiders probably the best matte ever done as its on screen for a very long time) while Digital CGI paintings can be held onscreen longer since the integration and lighting can be done the point that its seamless. However this involves alot of time and work that isn't put into every shot.

Not all shots in the prequels hold up, some do and some don't. But the same could be said about the OT. The Matte in Jedi of the Falcon is one of the worst Mattes ever done but its also in a film with one of the best (the Emperor's arrival).