You know, let's look at the time frame. Batman came out in January 1966 and a lot of shows tried to copy it. In September 1966, Batman producer William Dozier got another half hour show on, The Green Hornet. It had the same production values but the shows were more or less played straight rather than Batman's absurdity factor.
Maybe Roddenberry was trying to do something in that style.
More historical context: A lot of the spy-fi shows of that era were at least slightly tongue-in-cheek in tone. The Avengers, The Man from U.N.C.L.E.,
(As I've mentioned before, I used to play the soundtrack to Our Man Flint
when writing Gary Seven scenes, just to capture some of that cool Sixties spy vibe.)