Interesting list.. Tennis during the height of its popularity was shown on a major network station (when there were only 3). alongside the most popular programming. Competition was extremely stiff, and was a major sport. During that time, Bjorn was the best and McEnroe dethroned him ultimately causing the Swede to retire early. When Borg left, McEnroe lost the desire to compete.. and ultimately faded into the sunset.
Lendl reigned supreme at a time when tennis popularity started to declined and is now seen as a fringe sport. Sure, there are a few on that list worth mentioning, but tennis is not what it used to be. Not remotely close.
One should also take into consideration that the AO was not even looked upon as a 4th major since many top players skipped them altogether.