So Question/Discusson Time:
Why did neither Shovel Knight, Cuphead, or Sans get in Smash at a true playable level?
Personally, I think the argument "It's because Nintendo doesn't view Indies as important enough" ignores much about their connections and support for indie gaming as a whole. All have made an impact with their success stories. Nintendo has been promoting indie titles for the better part of a decade now. Simple Eshop art at first but now we have full on directs focusing on them. We even had a crossover between the Crypt of the Necrodancer and Zelda.
These three are some of the most popular current indie titles. I personally think they weren't chosen due to being too recent. They have yet to cement themselves as long running popular series, for the most part they have one or 2 games to their name. I feel if one has to be chosen it has to be a character with decent popularity and has a legacy.
And the two indies I think fit that best are Reimu and Shantae. With Shantae fitting the best overall.
I highly agree with the recency point. For Nintendo to include an indie character 1 of 2 possibilities come to mind:
1. An indie character is chosen to represent Nintendo's relationship with a particular company.
2. An indie character is chosen to represent Nintendo's strong relationship with indie developers.
With Reimu, yeah she's a popular character from a popular series, but Nintendo has never really worked with Team Shanghai Alice on games core to the Touhou series coming to a Nintendo platform. She doesn't represent Nintendo's relationship with indies, and unless they just want a Japanese cash grab she won't be chosen based on relationship with her parent company.
Quote has Nicalis to fall back on, but I can't see Nintendo coming up and saying: "We want to support our relationship with Nicalis." His other big negative is that he, like Shovel Knight, Sans, and Cuphead, only has one main game. Granted it's a really good game (good enough that Nicalis ports it to every Nintendo system ever), but I don't think it's good enough to justify his position as "the face of the nindies" like some think.
Shantae has a leg up over both of them in these categories. Yes, she may not be a household name in Japan or the West, but she's got legacy like Touhou and Cave Story, 5 games on Nintendo platforms, and Wayforward has multiple IPs and games all on the Switch. Hell, they've released more games for the Switch than ATLUS, and they got a character whose main game still hasn't made it to the Switch in Smash.
If Nintendo adds an indie to Smash and it isn't Shantae, I will be happy we finally get a playable indie, but ultimately disappointed because of how much Shantae has going for her.