Im wondering why the typical design is a warehouse with horizontal sprawl . Wouldnt it make sense to go vertical up or down .
Smaller footprint if insidea a metro area by having a skyscarper type data center , as i recall AT&T used to have such windowless anonymous buldings scattered in some cities for their equipment. Or have a Silo type structure going down if in a more rural area to not blight the landscape.With added advantage of dampenig on the sound pollution (although not sure what effects a humming underground building will have on subterrerean life).
Probably cost? All those would cost more that the biz are willing to spend , while putting up four walls and a roof is ordeers of scale cheaper.