Rack "foorprints" at the datacenter are expensive, and you pay for 15kw per footprint whether you use it or not. it just made sense to fit it all into one. Having had this rack running at full power for a couple of weeks now, I can say the temps stay lower than our SuperMicro racks in the same row!! and the Supermicro racks can only hold 20 machines before they run out of power in the footprint.
i would guess floor real estate constraints. Why do in 2 racks what you can do cost effectively in 1?
This would solve his thermal dissipation problem and probably be easier when compared to getting custom hardware.