I think it's mostly a traditional thing over a practical one, where that comes from I'm not sure but I should be seeing the man I know who learned the forms tonight so I'll ask him.
Lots of Martial Arts weapons are descended from farming tools, the idea being that these will be things that monks or peasants would have to hand, so they learn to defend themselves with them.
Wushu students are expected not just to wield them, but to perform acrobatics while doing so. It's all a bit mad that Kung Fu.