True, but if Paper Mario is going to go from being a Mario series defined by having stories and characters and experience points to being a Mario series where Peach doesn't do anything and Bowser doesn't say anything and there's no characters other than Toads and the only thing that separates it from the main series anymore is the art style, why even bother?
Sticker Star did a lot of interesting things and had some welcome fresh ideas, but there was no reason they couldn't have put all the good parts of it into an actual Paper Mario game. Having a battle system based entirely around disposable/discardable items and having an actual story are not mutually exclusive. Baten Kaitos had a card-based battle system and an interesting story; why can't Color Splash have both?
I would have forgiven them if Sticker Star was a one-off experimental thing where they didn't bother writing a story so they could focus all their energy on figuring out the gameplay system they wanted to use going forward, and then after that they'd be free to spend part of their time building on the system that they remade from the ground up in Sticker Star and part of their time writing the stories and fleshing out the characters, and four years later they could make a game that plays like an improved version of Sticker Star and has the worldbuilding of TTYD -- but no, they're just making a game that plays like Sticker Star and also still has all the character of Sticker Star.
The graphics are amazing, but other than that, how have they improved on Sticker Star? How have they built on it? The trailer they showed is just Sticker Star HD, except instead of peeling stickers off the walls everywhere, you hit circles with your hammer everywhere to do the same thing, and instead of paperizing to stick a thing in an empty space, you hit an empty space with your hammer and a thing fills in. The gameplay looks pretty much the same, and the characters are all still generic Toads.