Sure Zoro is strong and badass but as expected he's completely irrelevant to the Narrative as is his goal and Mihawk.
He is not and was never Sasuke. It's not an insult to say that Law is a more important character Post ts, just a fact.
I say its pretty simple.
Law is for lore.
Zoro's importance is that his strenght is needed to overcome WG.
Zoro is a man of acton monstly.
Nothing hapenned, hakkai, oden feat, and so on.
zoro is the cloest thing you will get to luffy strengh wise.
after that its luffy piece.
the reason oda is doing this is so that zoro dont outshine luffy.