Of course more people do watch on any given night.
1. Population was about 175 million in 1960. It’s about 315 million today.
2. There were 3 television networks in 1960. There are hundreds today, not counting internet connections.
3. Using the world series as a standard of interest in baseball, since it is the championship, just going from 1986 to 2012, the market share went from 28 down to 7, from an average of 36 million viewers down to 12 million viewers.
4. Therefore, not only is the population larger, but the interest is smaller by percent and by actual numbers.
Competition with other forms of entertainment and sports is also far greater than at any time in history.