I've been pondering this topic in relation to rewriting the prequels but thinking about McQuarrie's contributions does make it more vivid.

I agree with a lot of what you say. In the OT, there was so much focus and effort put into each prop and model and to make them believable on screen. They had to constantly work against the limitations they faced and used the simplicity to their advantage (eg opening of ROTS vs opening or closing battles of ANH).

Still, I can't help but feel that some important visuals were severely lacking in and of themselves. The senate chamber strikes me as one of the most boring executions of a galactic senate chamber possible. I liked the feel of Kamino (rainy scenes are awesome), but artistically never went more than puddle-deep, before letting us into another sterile environment. On Hoth, snow provided more intrigue. We knew there would a volcano planet but what we saw on screen didn't strike me as a very interesting rendition. I thought the Jedi Council chamber was weak. The visuals in the AOTC fireplace romance scene are boring - and it was not for a lack of trying nor intrusive CGI (only intrusive dialogue). It was quite a stylized scene in terms of lighting, costume and the room. But ultimately, even that simple and intimate setting didn't have any real character to my eye.