I'm sure there are a few exceptional hidden gems which I never played or even heard of that do have ingenious level design with terrains, but in a fat majority of games the terrain let that gameplay aspect disappear.

What makes you think that exploring a huge and beautiful landscape (terrain) with nice locations is no gameplay? It is just another gameplay.

Some people enjoy the freedom in Oblivion or Stalker. This is just a matter of personal taste.

Oblivion and Crysis have so far given me the best possible immersion..and they both use terrains heavily...the lush greenery,plants etc is so cool to look at !

I hoped I made the point clear by calling specifically to 'that gameplay aspect'. I was no talking about the whole gameplay, but about the missing element broozar described in his very first post.

gothic 1 was totally awesome, back in, duh, 2001(?). it gave me the "lord of the rings" feeling for my pc, with mines, monsters, sword fights, beautiful landscapes, towers, dungeons, etc. back then i didn't see terrain as a threat. the locations weren't too far from each other, and behind every stone you could find something new and astonishing. gothic 2 was critical. the world size had increased dramatically, but there were ony few major cities (cough cough). gothic 3 was definitely too large. i am not the run-through-guy, i want to look at literally ever stone and ask myself, how did they do it, isn't it nice, bla. gothic 3 was almost demotivatingly big. and i grew quite repetitive quickly.

in stalker, you have a time limit for certain jobs. so you are forced to do them and return to your boss imeediately. that causes a lot of extra-walking. example: in the first area, you have to crawl under the bridge with these electric discharges. the boss where you start gives you several jobs, and most have to be done behind that bride. so i always have to loose health in that crawlspace...

huge terrain is often, not always, a bad excuse for a lack of creativity in level design. "let's drop some huts in this field, add some more or less intelligent bots and brand it >great freedom<.

Yes, I agree, but it's also a great example how they still actually did some proper level designing.. instead of using the terrain as an excuse to generate more space, but not really more gameplay,

Cheers