I've heard of two reasons why pro's shave their legs and neither reason is because it makes them more aerodynamic. (There maybe some evidence that hairy legs actually increase aerodynamics; the hair my hold a boundary layer of air. Think of dimpled golf balls. Also several riders in this year's Tour are sporting beards. If hair really affected aero, those guys would probably shave. And there's Pocacar's hair sticking out of his helmet all over the place)
The first is to help with road rash and scabs. A second reason I've heard is to make it easier for the masseuse that travels with pro teams to give them their after ride rub down. Since few of us mortals have a masseuse on retainer, I think that excuse for shaving goes away.