Metascores aside, the sales are indicative of a couple of things:
1) The Wii U is dying. Even if the game is crap, the attach rate would have been much better even a year ago. This game released when the Switch rumor mill was at its peak, and people weren't really thinking about the Wii U anymore. After another year of bad game droughts, I'm not at all surprised this title pretty much flew under the radar at release. Wii U owners largely don't seem to be paying attention to new releases and are happy with Smash, Mario Kart, and Splatoon, or are simply jaded and refuse to invest anymore into a system Nintendo failed with.
2) This is not the Paper Mario game people want. I mean, c'mon Nintendo. Since the Wii title, fans have been asking for a return to form, and instead we keep getting games that refuse to meet the standard the first two titles set. Especially after the crap shoot that was Sticker Star, did Nintendo really think anybody would be clamoring for a game that fails in one of the major ways the previous game did? This is a clear example of Nintendo not listening, and I really hope they stop thinking they know better than they did when they made the original games that people actually liked. This is not a case of age crafting wisdom. I don't need a TTYD clone, but a Paper Mario game that utilizes more traditional JRPG combat and growth in fun and active ways would be stellar. No one asked Nintendo to remake the wheel here.
I honestly don't know if we should blame the dying Wii U more for the lack of sales, or the fact that Paper Mario fans largely don't seem to be willing to feed into Nintendo's oblivious approach to game development anymore. At what point do you decide that maybe keeping the series alive isn't worth it if you won't get games like the ones you liked anymore? Even if the next Paper Mario game flops, if it matches up to the first two, I would be okay with it being the last hurrah because at least Nintendo would have finally listened.
