Exactly. Full server = Regular game. Near-empty server = Bad gameplay, which means you might as well goof off until more people show up.
This is especially true with FS, which currently has a small player base. If I log on and there's many players on, I want to fight, not race around on speeder bikes or throw a "party".
"One of the bitches actually gave birth while she was attacking, and her puppies joined in on the carnage."
--the awesomeness that is Boatmurdered.