People actually don't notice that Oda doing this is wanking Zoro to heaven.
I'm pretty sure Oda didn't make Mihawk teach Zoro about sword skill because of a lot of things, for example :
1. The implications that Zoro already have peak level sword skill, so he doesn't need to be taught that, only Haki left.
2. The realization that Zoro "will create his own path" instead of following Mihawk's style.