It isn't useless per se but how Oda handled it is laughable. No matter how much of a Zoro fan you are, I can't see any intelligent reason why anybody would rather what we got (Mihawk and Zoro bromance) than an actual race for the title that includes defeating people with the same objective but different styles, philosophies on swordsmanship, morals, etc.
Only Zoro and Kuina have shown actual interest on this title; Kuina is dead and Zoro was trained by the current holder. Zoro's whole dream doesn't feel like an actual challenge but narrative endogamy at this point.