The problem is this:
Oda parades the entire Straw Hat crew as the main cast, which is pretty much irrefutable, but then the only characters besides Lu/ffy who get proper focus & development besides Lu/ffy are the characters who just endlessly worship him and whose entire character arcs revolve around him.
Is that not a valid criticism? For some reason, you guys just write off any complaint that involves Nika as "well too bad, he's the MC." Everyone knows that. Everyone expects Lu/ffy to be the one to defeat the biggest villains, to have the most panel-time, and to have the most focus.
All it would take is replacing a few extra panels of people running around doing nothing or the 200 *shocked face* reactions we get