Afros are funny.
A particularly large one, no matter how awesome, can be a liability. Especially in physical battle.
So why do countless badasses, many of whom know karate, have them? Because they're funny and awesome. A sub-trope of Funny Afro, an Afro Asskicker originated in America's Blaxploitation era and are usually black Americans and / or connected to the tropes Jive Turkey, Soul Brotha [...] [tvtropes.org]