Related- I recall the actors from the Willy Wonka remake expecting to have to walk past green screens pretending to see amazing things, and were actually quite surprised when they made a legit chocolate waterfall and legit environment. And it looks all the better for it. (no matter what you may think of the movie itself)
The thing about CG vs real props/sets is that the Human eye can tell the difference.
The Human eye can pick up the small details when something is CG. And its something which can become distracting, because you know it's fake, its not really there. Its just a trick.
However, with real props and sets, you cant really tell the difference. They look real, because as previously said, they ARE real. You dont have to fake the lighting on it to match the scene, you just shine the lamp on it with the rest of the actors, you dont have to fake the interaction either. You interact with it like any other actor, and you see the finished product as a little green alien as actually being a real alien.
Ships and space stations in the original trilogy looked so cool because they were props. Miniatures shot and edited to look full scale. Therefore, what you see, is a real spaceship made of real materials which really works. In the prequels however, its not as interesting due to just being able to work because its CGI.
If I recall, the CGI in the prequels wasnt exactly the best either. It was way too easy to tell what was real and what wasnt. In fact, I think that its one of the reasons why the movies are so uninteresting. Theres SO much CGI used, thats its like, an overload. Like when you have too many Twinkies or eat too much. Its an overindulgence of something so uncanny as CG sets environments and characters that you sort of get turned off by it all. I cant really explain what I mean... But its just that something about having SO much CGI, CGI which wasnt exactly the best either. But then again, they came out from 99 to 05, so I cant exactly judge them with comparison to today's CGI.