>>717542847
>a game this easy doesn't need a button that make impervious to pretty much everything
a) A guard or shield is definitely appreciated in a game like Kirby. Ever since Super Star, each game seems to play like a fighting game to an extent, where every copy ability has their own moveset. The shield button adds to that feeling.
b) Gordo is a typical foe in most Kirby games, and you can't hurt him. Plus, he's not the only enemy in those games that can't be damaged. 
c) Kirby is for kids, so it is fine to offer some level of leniancy for them even if you, as an adult, perceive as an easy game. Remember, those games are developed so they can be completed by children. 
d) The game doesn't force you to use the shield button. In fact, just last year I beaten Planet Robobot's True Arena in a no shielding/no copy abilities run.