Jedi Outcast has ingenious level design as well. I recently started playing it again. No terrains whatsoever, only blocks and models. Everything is connected and you visit places sometimes more than 4 times on your path and thinking: "Ooooh, thís is how the building looks like". Taking a long walk killing imperial guards and stormtroopers, open a door and you're back at the start, but achieving that shortcut makes everything very clear and easy.

So in that context, I totaly agree terrains killed that aspect of gameplay.
A combination is still the best though.