That'd be a pretty bad way to go...
Re: Polearms, it be a great thing to do, but arguably it would be a problem if the blade would get stuck in a zombie head as they often are, allowing others to get within munching range. It has merit, but I think the group hasn't had that much time to think about it, create the weapons (even by tying a knife to a bamboo pole) and training themselves accordingly. We see they've become adept enough at taking out small groups and running away when needed.
On the plus side, killing zombies through fences came to them pretty quickly. "In the comics...":