This guy is really making good points here.
I would have to agree that Players will simply do what is most effective. If that happens to be a zerg, it will be done pretty much.
In ACP final fight with the crystal, you had 2 methods of beating it, the Zerging method or the Ranging method.
I beat it with the Range method but lost to the zerg method.
But both methods are fun to do if you execute them right.
So ya. =)