I agree with Rafa in one thing
Tennis matches like between Sampras and Ivanisevic were not entertaining even near like matches between Djokovic Federer Nadal and Murray. These matches were simply serve serve serve ,few swings with racquet and thats all.
Maybe some of you miss that but I like to see matchups with long exchanges lot of variety , slices, volleys and of course baseline fights with winners.
Thats tennis which I like to watch , and for that kind of entertainment average speed courts are the best by my opinion.
Matches between guys like Sampras/Ivanisevic were just one aspect of that era, and the exception rather than the rule.
The good thing about the 90s was the variety. You had power S&Vs (Ivanisevic/Becker), touch S&Vs (Edberg, Rafter) counterpunchers (Agassi, Schuttler), retrivers/defensive baseliners (Chang), offensive/power baseliners (Courier, Kafelnikov) spin kings (Brugera, Muster) and occasionally a prodigiously talented all-court player like Sampras.
Why so much difference? Well, the diversity of courts means you couldn't hope to be equally successful all year round. Players tailored their game to a specific type of court, and cashed in during their surface's 'season'. The best players were competitive even on their less favoured surfaces, but they would still be at a bit of a disadvantage. The number one player was the guy who dominated his favourite surface, and then managed to succeed the best on his non-favoured surface.
Nowadays, the higher bounce and lack of penetration on pretty much all surfaces means that with the right style of play, you don't really have much of a disadvantage on any court. It encourages everybody to adopt the same style of play - primarily defensive, with power used to move people around and draw the UE rather than hit through for winners and FEs.
Don't get me wrong - long rallies with impressive physical displays and big shots coming back are great to to watch. And we used to get that - at the French Open. In the 90s if you hated endurance baseline tennis then not to worry - the clay season's almost over, next up is Wimbledon. If you don't like short points and power S&V - no big deal, in a few weeks we'll be back on a more medium-speed surface with the hardcourts in the US.
The sheer lack of diversity in modern tennis is a killer. It used to be one of the great and unique things about the game - different styles, different strategies, different winners at each tournament. Constant changing, duels between two players that would be vastly different depending on where they were played. Nowadays it's the same thing being served up all year round.