Only two reasons:

-First, the aforementioned road-rash reduction. It really does help with cleanup and dressing
of wounds.

-Second, Most ladies like it. A lot. Perhaps the best reason of all.

You probably should not shave them if you are concerned about what the guys in
the office sports betting pool might think.

I've been shaving them for decades now. I like the look and feel, and no, I am not concerned
with what anyone else thinks.

Besides all that, aren't we all supposed to "celebrate diversity" these days?