Yamcha is weak but it's not "THAT" weak, give the poor guy a break!
Yamcha at least leaves a whole body behind 90% of the time, that says a lot of his sturdiness. Meanwhile yukkuris 90% of the time are splattered or ripped apart easily leaving only pieces and filling, and to add salt to the wound, this happens with guys with no training or natural ki affinity! Yamcha would probably need a freezer tier of power level to be blown up to pieces as easily as a yu, meanwhile a yukkuri only needs a "baseball bat" tier of power level to be splattered around.
I still think that Krillin/Kuririn is cooler though, but that's just me.