This may be just me being impatient, but I often hit the Google cache if the site isn't down, but just responding slowly at the moment. It's a nice convenience factor when I'm looking for something quickly.
As such, it annoys me when sites disable the caching; if a site with no cached version takes more than a couple seconds to respond, I generally go elsewhere and will probably retain a negative impression of the site.
I also note that neither of his two reasons for blocking caching have anything to do with improving the user's experience.
On the other hand, I'm not the target audience for most sites, so it probably doesn't matter much.
