Consider me less than impressed. At elite competition levels where winners are determined by <s>doping/transfusion</s> hard work and micro-optimizations, sure. Mortals can worry about anything else.
Edit: According to this random site (https://cyclinglevel.com/cycling-times/40k-times), an elite rider can complete a 40k in 75 minutes. A 70 second reduction would be a savings of ~1.5%. Meanwhile, an intermediate rider should expect to run the same course in 88 minutes (~17% worse than the elite with hairy legs).
Otherwise most of the riders will rotate through the peloton (group).
Don't get me wrong aerodynamics is important and yes it is of most importance during a time trial, but that's about it. Otherwise they wouldn't shave their legs all year round. There are many other reasons why professional cyclists shave their legs that are just as important.
I don't think the increase is surprising at all, it's been known for a long time.
Tour de France level riders shave their legs for a combination of reasons 1. Aerodynamics gain (albeit small) 2. Reduces the pain of massages on hairy skin 3. Don't have hair sticking to bandages and 4. Looks.
Much like what has already been said, for the majority of us it's likely just for aesthetics and perhaps sunscreen.