A specific example of this I can recall playing recently was in the level before Composer in Halo 4 (sorry, I can't remember the name - the one with the Pelican). There's an area inside one of the towers with two moving gondolas. When I first explored that area, I had a really hard time figuring out the layout, where I could safely walk, how close or far things were, what the intended route was. There was so much detail and crazy shapes that it lost all form for me. Of course, after playing through it I was able to figure it out, but it was still hard to look at and appreciate. You really had to move around a lot to figure out the dimensions.

Perhaps it's completely a personal thing. I just like to approach visual design with a clear layout up front, with a few important areas of focus - but not too many, or they all are lost in the confusion. Then, with this basic layout you can impress upon the viewer something with an impact, like a Halo ring stretching up into a clear blue sky. You seed your details as more of a secondary effect. After the big impression has been made, your audience starts to notice the little things like the continents, oceans, and weather across the ring, or the dim stars around it as the blue sky fades into night as you look up.

Or in terms of explorable structures, say you see a monolithic structure rising into the clouds in the valley ahead of you. From afar it appears to be a seamless, alien-in-construction monument, but as you draw closer, you can clearly see walkways and paths to climb and enter it. Then getting even closer, you see strange patterns and steel reflections in its surface - little details that reveal just a bit more of its origin.

That's how I would describe the original Forerunner designs. But now, like with a lot of games, its seems like things can't be left alone to sink in slowly. That monolith today would have lines and nuts and bolts all over it (which would destroy the dream-like, alien effect), and when you got up close, it actually wouldn't be very pretty at all because it was designed to hit you over the head from a distance with high-geometry/low-resolution shock. And instead of leaving the monolith to look strange in a typical mountainous environment, today the mountains would have to be as jagged as possible and they'd shoot green fires out of their peaks or something.

Obviously, I'm generalizing and not ALL games do this ALL the time, but it's definitely something I've really started to notice within modern Halo and other modern sequels (it's not a 343i-specific issue).