I shave legs for post crash comfort (I get tot skip the painful ER nurse's shave; they always thank me, there is less abrasion of the skin around the raw meat, bandages pull much easier and with less pain and everything heals faster).
For the crotch, I use a trimmer at the closest setting. My concern is the hairs being pulled. (I have the common male problem of my hair mass staying constant but the center of gravity is shifting down. Head going bald and down there making up the difference, So those hairs far longer than they used to be love to get caught between chamois and moving parts. I oly trim those hairs that can actually get caught. (In other activities, shaved clean is good, full length hair is good, short bristles bad.)
Ben