They use 120v equipment because that is what they make for the consumer market. When a data center uses 240v it is to avoid having a neutral and the associated noise in the room. They want it all to be line to line. In fact we didn't even bring a neutral into the data center panels before 120v PCs became so common. Everything, including the monitors and small controllers was 240/208. There was a "convenience" transformer, 208/240 to 120v in most of the frames but they didn't ground either leg of the output.
When small switcher supplies came into the market most of those concerns went away and we started seeing 120v stuff all over the place.
The design assumes you will have a branch circuit with O/C protection based on the line plug and they have overload protection in the power supply so you won't need unusual breakers.
