I wish Oda could break off from the post-skip trend of storytelling that is more sales-contingent than passion-driven, to write a story with the aim to universally move an audience instead of oftentimes making writing choices catering only to the popular components.
I wish Oda would stop the clumsy transitions between places as a means of conveniently off-paneling events.
I wish Oda could develop the story by developing existing characters instead of constantly creating new ones, and to lessen the over-focus on short-lived side characters.
I wish Oda could take a step back and reflect upon what actually made audiences fall in love with One Piece during the early days and establish this manga as one of the giants, the heart of his story - the Strawhats and their personal goals of achieving their dreams. That he would reinstate their integrity and place in the story and give them their due attention and weight to drive the storytelling in an impactful manner with their individual strength shining through, and not be relegated to side-characters often helplessly observing the whims of their captain.
Even though it's a shonen story, I wish Oda would realize that his fanbase is getting older, not younger.