Heck, turn her into the villain because she's tired of being treated like a MacGuffin! The game does humorously poke at Peach's trope-y and stagnant role in the series towards the end, but I'll let you find that on your own.
Of course, it'd be nice for Peach to get some agency. It's a reason for yet another set of platforms to jump on. It's a setup worthy of an eyeroll, but outside of the RPG spin-offs, Mario's never been about plot. Each of the worlds contain an object Bowser desires for the nuptials, which sometimes explains their theming (a food world for a cake) and often doesn't matter (a water world for a dress). This time Bowser's goal is getting married. Once again, Bowser's kidnapped Princess Peach, and Mario has to save her.
