The power is only relevant because it makes the machine quite in a compact form. If you've got a bit of space, then a water cooled system accomplishes a lot of the same thing. For some people there is an aesthetic element.

Power does make a big difference in data centers though - it's often the case that you run out of power before you run out of rack space.

Where power for a computer might make a difference could be in power-constrained (solar/off grid) scenarios.

I don't know if I've ever heard anyone make an argument based on $$$.