DS9 wanted Worf to be a little funnier
One of the best things about Worf, the Klingon who made his debut on Star Trek: The Next Generation back in 1987, was his ability to make even the most serious of lines humorous. Along with that was the one-liners he interjected when protesting, i.e., “Klingons do not faint.” And who can forget “I must protest; I am not a merry man”? Michael Dorn had a way of delivering those lines that made them hysterically funny.
Over the course of seven seasons on The Next Generation, Dorn was given plenty of good lines to work with, but Dorn said that even if the writers handed him a cute line, he said it the way he wanted to say it. And perhaps it was the way he had with those lines that made the producers of Star Trek: DS9 interested in making the Klingon funnier, a move which Dorn protested. [Star Trek All Good Things: A Next Generation Companion]
"“I’ve got to say, on DS9, they made an effort to try to be funny, to make Worf funny, and when I protested, I got a lot of resistance…”"
Forced humor would have changed Worf
Dorn’s delivery of the lines made them naturally humorous. An attempt to force the humor could have backfired, and Dorn admitted that he got protective when the producers insisted. It’s not surprising he stood up for the character. After all, who knew Worf better than the man who’d played him for so long?
"“I played it for real, not for comedy, and that brought out the hilariousness of it all.”"
Klingons weren’t known for their sense of humor anyway so it makes complete sense that Dorn would want to maintain Worf’s level of seriousness. In addition, as warriors, Klingons didn’t generally stand around telling jokes, and the only times they had moments of hilarity were usually after a battle they’d won. Smiles were a rarity for them so making Worf into a funnier guy would have looked out of place, especially after he’d spent seven years aboard the Enterprise in a very serious capacity.
Fortunately, the producers listened to Dorn, and Worf wasn’t changed into something he wasn’t. Something that would have lessened the character.