Personally I haven't seen a scenario where it makes sense beyond a small experimental lab where you value the ability to tinker physically with the hardware regularly.

Offices are usually very expensive real estate in city centers and with very limited cooling capabilities.

Then again the US is a different place, they don't have cities like in Europe (bar NYC).

If you are a bank or a bookmaker or similar you may well want to have total control of physical access to the machines. I know one bookmaker I worked with had their own mini-datacenter, mainly because of physical security.