This is wrong, actually. The current crop of watercooling solutions do exactly that, push cold water from large radiators mounted outside the building all the way to the individual CPUs. The term used for this is DTN, or "direct to node" cooling. This greatly reduces the energy cost of moving heat out of the system, by Lenovo's account improving energy efficiency by up to 40%. In traditional air-cooled datacenters in general if you spend a watt at the rack, you have to spend another watt to get that out in the HVAC system. Apparently it's much more efficient to do this with water than air.
I can't comment on how much actual adoption this is currently seeing, but it's definitely the new hotness that everyone talks about.