Gotta say, I love your logic here Jack. I'd write more about it, but I think you summed up pretty much everything in this quote from another thread:
No one is going to want to play a level that is boring. That's why it's important to not only vary the textures every once in awhile, but vary the shapes, sizes or rooms and vary the linearity (if that is a word...lol) of the layouts themselves. Also, finding interesting new object and guard placement makes the experience more enjoyable for the player.
Mmmmm, variety in every form is so delicious. This conversation is making me hungry, I need to go nuke a pocket now...