Reality set in. The tides starting shifting after Kennedy was assassinated. The beatniks and the beat generation have way to the hippies and war protestors. The counter culture took up the mantle of free love to counteract the atrocities of the war.
Meanwhile, in the background, the civil rights movement came to a head. Suddenly, minorities were no longer just minor, background characters, usually maids or porters, but became leading characters.
Lastly, the envelope needed to be pushed, as most comedies relied on formulas created in vaudeville nealy a century earlier. Using the same routine for years, although honed to perfection, grew old, fast. Everyone saw it at the same time, so you couldn't do it week after week.
