So... why do you think Bokuto wears thigh highs? Personally I think it's cuz his thighs are too powerful for regular knee pads :3c
That’s a good and pure headcanon, my love, I approve it 100%
If you want a serious reply, I think that the thigh high knee pads go along with the “basketball” aesthetic that surrounds Bokuto. And long kneepads are really really popular in basketball.
The biggest clue of this is the number he wears, the 4, which is the number of all the captains in KnB, if I’m not mistaken, and (I couldn’t find the official source for this) apparently the creator of KnB worked with Furudate, teaching them how to draw sweat and attacking positions. Bokuto could be a character whose aesthetic was bestowed to them. This sort of thing happens, even in big productions (Rei Ayanami, one of the protagonists of NGE, is a tribute to Rei Hino, from Sailor Moon).
- the official explanation though, could be that the 4 is the number of the ace in Fukurodani, and Bokuto prides himself to be the ace way more than to be the captain -
If you want MY personal hc, he wears high kneepads because
Akaashi has a thing for his thighs and he covers them in love bites all the time so Bokuto had to find a way to cover them ( ͡° ͜ʖ ͡°)