Rewire switched bathroom receptacle to always be hot
I doubt anyone would intentionally wire a bathroom receptacle this way.  They either made a mistake making the connections / splices, which can easily be corrected, or they ran the wiring wrong, which is more much difficult to correct.    

You can correct the problem without correcting the wiring if you convert to a smart switch.  If the switch box doesn't have a neutral present, this will limit your choice of smart switch, but it is still doable.  

You could also remove the switch so the light and receptacle always have power, and use a light with a pull cord switch - it's perfectly sound electrically, but it's not really done in the US any more.