True. Most "bites" illustrate a scientific point, but a few, especially those tagged "humor" are included purely for the entertainment value, to help wake up your audience, share a laugh with them, and help connect with them.
Humor is amazingly powerful. Nothing gets an audience "on your side," makes a speaker seem likeable, having shared values with the audience and worth listening to -- like sharing a good laugh.
We've seen debates where a scientist marshals reams of accurate but boring facts to make their case, while his opponent just tells some great jokes. The scientist thinks he's winning, but guess who the audience sides with when its over?
See Tools/Humor/Why Humor is Important