The price of a videogame never defined the length of a game
Oh, I know. But it is about getting your money's worth, and while length isn't the sole factor, it still *is* a factor in how much a game is worth. If you were to be mathematical about it (a bit too
mathematical), you could say that a game's worth is an integral from 0 to game length of a function 'worth over time', which would be a plot of how much you're enjoying the game over the time into the game.
And with how much the game plays itself, there is very little enjoyment over time. This would be okay if the game were long, since I'd then still get a lot of enjoyment out of it. But not when it's short. At least I won't get 60 euros' worth of enjoyment.
Multiplayer in a Kirby game was never for me and offers zero replay value. In a Mario game (like Super Mario 3D World), everyone can kinda jump around in their own way and have fun that way, but in a Kirby game, you'll be stuck waiting for each other constantly or watch how the others clear the obstacles