I spend quite a lot of time in a datacenter, and the back of a rack is most certainly accessible by opening the door in the warm corridor. (Otherwise how would you attach power and network cables to the servers?)
I didnt say it was totally inaccessible, but no one wants to through the back, and wade through the cable mess, move cable management arms and get your fingers cut just to turn a machine on or off, or reset it.
My racks are very neat and tidy at the back. But you do have a point if you're somewhere like this:
http://jeffreydonenfeld.com/blog/wp-content/uploads/2011/04/messy-server-rack.jpg
