I think a lot of BWD fans don't realise that him being a main character with lore prominence is the argument against him. His detractors don't think he's unimportant, they moreso don't want a character so hastily put together designwise to be important, especially when Kirby has a whole pool of great sidekick characters they're sitting on (Rick, Adeleine, and Gooey to name a few)
I am very curious to hear your reasoning...