Let's put that way. Some people build datacentres. Some other people don't. The guidelines of people doing it, are little more interesting than the guidelines of people who don't. Is a crazy world, man.

Mostly blueprints from companies like Cisco, IBM, Google, and so on.

Well, not "a little". The one you described is - at best - a server room, not even a hosting center, since according with the blueprints, there was no redundancy....

In the first sentence you mention a "data center", but such an attack would not work with a data center, to be one you need to have two buildings with independent power supply, at a safe distance, etc etc. I think this was at best a hosting room, not a data center.