As someone that flipped the power switch on a rack mounted machine by accident before, I could see how a power button or switch would be consitered a liability

As someone that flipped the power switch on a rack mounted machine by accident before, I could see how a power button or switch would be consitered a liability more than a benefit, especially when the solution (pull the power cable) is simple, foolproof, and doesn't happen that often to warrant optimizing!