They but him in because he is the ultimate spanish pimp! And he is a really good character, i mean, hhe was always in DBZ, only in the buu saga did he fade out abit, but he wwas still always there with goku, fighting to the bitter end no matter what (except with 18). Krillin is the best char in the whole show, unlike goku vegeta and co' he is actually funny and unpredictable, all goku does is say silly stuff, scratch his head and go SSJ and kick ass.