Because that is the only thing Zoro's character had this entire series. Epicness.
Which is why he is different from Sanji. Sanji is all about his personality and character over glory and epicness. I am not saying Sanji doesn't have his epic moments but Oda chooses to highlights his traits more and make him the background hero no one knows about.
But Zoro will always be epic and glorious :cheers: