The time and place for humor on Jeopardy is totally different than that on Family Feud.
I agree with you completely. Jeopardy and Millionaire are both what I would call "hard quiz" programs. The accent is very much on knowing a hodgepodge of different areas of trivia. While they're not COMPLETELY serious, and there's some lightharded moments on them from time to time, the emphasis is very much on the gameplay. Not too much room for a comedian to make light of situations here.
Then we go to Feud, what I would call a "fun game show" as compared to the "hard quiz" I spoke of above. No trivia here, and no way to really "bone up" on the subject before you enter the show - you're trying to predict what 100 people said, and the answers may not necessarily be "correct". Not only that, but under pressure, sometimes a very silly answer will be given. This is where a comedian comes in, to really magnify the situation and milk some laughs out of it. This is why with Steve Harvey, the show's ratings improved. He is very good at that.