raised flooring is a holdover from the 60's and 70's when large mainframes that required air cooling had a hole in the bottom of them and the air was pushed form under the floor and up throug the chasis. most are not designed like this any more - some are even water cooled. any way- unless you have a mainframe shop that requires it - there is no use for it - especially in most current colo environments. I have worked in many raised floor mainframe and colo environments since the mid 80's and there is no need for them now. most people just dont know any better and as karl pointed out - its the lemming effect - people just do it because they think you are asuppoed to.

in fact you get heat loss problems in raised floor because you are cooling the floor that the air is forced in direct contact iwth. not good.