Oda likes to give Straw Hats opponents who play to their weaknesses, and therefore gives them something to overcome during the fight. Zoro specializes in CoA, so what challenge does Kizaru, a Logia which Zoro has proven he can cut, pose for Zoro to overcome? His speed? Fujitora being a Swordsman, who seemingly specializes in CoO with massive AoE attacks thanks to his broken devil fruit, narratively fits Zoro better as a challenge to overcome.