Surely you would want to be able charge up your cell phone while you were using the facilities would't you? I wonder if 12 volt
RV appliances were (or are) available such as electric razors and the like? Maybe this type of outlet is intended to help curl your hair (you can stick you finger in to see if this works).
I basically have the same question that you do. I am in the process of completely reworking my AS and wonder if I should maintain the 12 volt
outlet there or not. My service manual tells me that some of the 12 volt
outlets in my rig were extra cost options. I don't remember if the one in the bathroom was or not. I think the one in the back bedroom was though.