A lot of folks have written more thoroughly and wisely about the early years of MNF and why they were successful. Still, I think they overlook one enormous point, one that is nearly unbelievable to us today: at halftime, they showed highlights of the Sunday games. This proved so popular that it began taking up more and more space in the halftime and postgame shows year over year, and rapidly ceased to be a novelty.
Before 1970, and on most broadcasts for a decade after, you got to watch the stadium's halftime show, with local high school bands and twirlers, plus lots of commercials.
Before MNF, that video was hard to come by. Some of it would show up in next week's NFL pregame broadcasts. Except that there weren't many NFL pregame broadcasts. One was lucky to see video highlights of the home team's last game, never mind anything else from around the league. One could also wait until about six months after the end of the season and buy the season's expensive highlight film for your team. Or next year, there would be a special broadcast of the champion's season, with highlights and slow-motion, narrated by a single voice in stern tones.
Cosell's odd cadence and elevated vocabulary were an irritation, but a fun irritation. Don Meredith was a fun-time boy who pretended to be a rube - sort of a Joe Namath with 20 more IQ points. Frank Gifford was a respected old-school player who grounded everyone in a quiet, authoritative way. Their chemistry has been the subject of countless essays, even academic analysis. But I'm telling you, it was the highlights that amazed. I was a college boy, and people would chatter, shout, and complain throughout the whole Monday night broadcast. But at halftime everyone got silent and serious and strained to hear. You could say "wow..." or "oh boy!" or exclaim one of the player's names, preferably his first name: Earl!! or Merc'ry!