You don't want your own office. If you really hack someone off, they will seek revenge by, say, hiding a rotting fish in there. You'll notice the difference between confined space vs an open area for an attack like that.
Dilbert's logic in the first panel is wrong. Even if the studies are right, being more intelligent does not always make a person more productive. In the second panel PHB's logic is also flawed because Dilbert's intelligence could still be "high enough" to figure this out. ... But then again he didn't... Never mind. I may have been working in a cubical too long.