LEC have been known to make cheerful and humourous games (Sam & Max, Monkey Island, etc) I mean the ADVENTURE games, not the Star Wars franchise.
However Grim Fandango is not cheerful really, in fact it could be quite frightening to an untrained eye: The sadistic baddies, undead corpses and who can forget the disgusting sprouting (shudder)
Also GF have also killed off several characters for the first time, Monkey Island has never had a character destroyed in the arms of the hero. Manny saw Lola being sprouted having a morbid and emotional effect on the game- no one is safe, even when your dead.
Though Manny is dead (and is not harmed) he comes to some very near after-death experiances, such as the final scene with Hector. Guybrush has also passed-by his own death-like experiances with a funny and sometimes riduculous ways.
Was LucasArts playing deathly with this game, being set in an after world with dark corners and smoking?
(at least the jokes were good, though sometimes adult)