Sherwood Schwartz gave birth to Gilligan and the Bradys, yes, but he was also a veteran of 70 years of comedy. (Dude was born during World War I, after all. He began writing radio jokes for Bob Hope in 1938.)
Sherwood Schwartz 
“I knew what was wrong with the show. Here’s a guy, Red Skelton, who’s a clown. Very funny! But… you cannot give him a verbal show. You have to give him a show where he’s in motion, where he does funny things. And they were doing a show that was 80% verbal and 20% funny.”
“Now Bob Hope is not too good at moving. He doesn’t move funny. But he talks great. And here’s the reverse of that.”
The whole set of Sherwood Schwartz interviews is warmly recommended if you’ve got minutes (or hours) to kill. It’s helpfully indexed by topic, so it’s easy to skip around and hear him talk about writing for Hope, the casting of Gilligan’s Island, etc. (Tina Louise was told that the show was “a story about a movie star who is stranded on an island with six other people.”)