It isn’t about just having the stages, it is about the original Katamari being the perfect complete package. From overall art style to even the story itself. It is easy to overlook those kind of things (especially because of the “wacky” way they are presented) but all the games after the original two had a kind of “off” feel to the side stuff for me. As if they got the bits and pieces right but was missing out on something internal.
Like I can’t say they are my absolute favorite games but I do feel that the original two Katamaris are “perfect” games. Second being the perfect sequel to something that didn’t need a sequel. Unironically made as a love letter to the first game.
Or maybe I put too much thought into a series of games about rolling things up into a ball.