It's interesting that Peter Jackson noted that the conceptual designs of movies no longer seem as cool as they used to (probably most especially in the case of Ralph McQuarrie). Why is this, did Jackson say? Is it because people are less imaginative than they used to be or because it's all been done before? Not really - although those might play a role in it.

The main reason is because nowadays, anything you can imagine can be on screen. When you look at McQuarrie's designs for the OT, there are tons of little details which you know couldn't be achieved because of time and budget concerns - such as the saddled pterodactyls on Bespin or the giant Ewok eater beasts on Endor.

But for the PT, Lucas could go, "I want a giant underwater monster for Naboo." And they could go, "Sure. How about three?" "Great!"

I think that this somehow played into the sometimes lame nature of the PT visuals. (Although I agree that Kamino was pretty cool, and I also thought Mustafar was good, although McQuarrie originally contributed to that aesthetic, too.) I think that the focus on prioritizing and the agonizing over details probably aided the OT.

Also, I think that the digital artwork nowadays - with its algorithm-generated color transitions and synthetic flares and sheens - simply doesn't resonate as deeply with viewers' subconsciousness as a hand-painted matte.