Top college athletes and pros shave their legs for a reason. They don't do it for aerodynamics or anything like that. When you are doing plenty of speed work, mileage, etc., you need to take care of your body. That includes getting massages quite often. If you have hair on your legs, it can be uncomfortable when the trainer works on your legs or rubs them down as they work up the leg, thus against the hair. By shaving your legs, you make it easier for the trainer and yourself.
If you aren't getting your legs worked on a pretty consistent basis, then there is no reason to shave your legs unless you like the feel or look of it.
Most people just assume its for aerodynamics because they don't know any better, and I don't blame them.