Interesting thread to read through.
I think level designers are very underestimated in the game design industry. Environment artists get all the credit for making the awesome-looking models/textures, the people that make the game immersive through gameplay don't get as much credit at all.
However, it's the same with other mediums of entertainment, film/television script writers tend to not get a lot of credit, it's the actors and/or cinematographers that get most of the credit.