Fast clay courts just show how ATP wants to homogenize the game. There are two surfaces that should've been left where they were, grass and clay, the two natural surfaces. HC could then be adjusted to be between them, I'm mainly against surface homogenization but I think '90s HC were too fast on average. I think USO and AO had the correct pace between '03 and '07.
Problem with extreme low or fast surfaces is that promote specialists with a monotonous style, zero variety and very predictable tactics. Tennis fans like those matches where they can see a bit of all and players can and even must to show some complex and varied tactics. And mixed surfaces allow these scenarios. People don't like to watch two single tricky ponies playing for three fucking hours in each round. Homogenization of surfaces is a trade-off between 'macrovariety' and 'microvariety'.
It piss me off the monotonous and simplistic point of view with people usually address this issue, at least in this site.