is the exception here, not the rule (and even it had more humor than its reputation for bleakness). I don't think the charge that sf in the 1990s and 2000 has much merit.
Consider Stargate SG-1
, Stargate: Atlantis
, Red Dwarf
, etc. Even The X-Files
, for all its conspiracies, tragedy, and dark cinematography had plenty of humor, featuring comedic characters like the Lone Gunmen on a regular basis and frequently producing entirely comedic hours.