That's cost ineffective. The sheer scope of the worlds on the PT blow those of the OT away, visually. To make models and sets that big or that vivid would cost more than they were worth.

However, I would be happier with sets that were on a lesser scale, if they looked realistic and not like CGI. I wouldn't mind that they weren't as big or vivid.

I'm one of those people who thinks that the less resources a good director has, the better the movie (to a point). With less gimmicks and effects to fall back on, the characters and plot become better to sustain interest. That's one of my favorite theories about filmmaking.