Not a comparison though.
When Lucas was beign added to Brawl, Sakurai didn't even knew Mother 3 was Japan Exclusive, and wouldn't have added him had he known otherwise
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and blah blah Marth and Roy were supposed to be Cut blah blah we knew this already, and as soon as FE7 was released they made efforts to localize all following entires, Lucas and Roy so far are the only Smash Characters in the roster whose games haven't been localized, and they will likely remain as the only ones in the distant future (until Roy's game gets remade ala Gaiden).
The thing is, Smash back then is different from what it is now, it seems Sakurai is far more focused on making Smash appealing Worlwide, adding characters that appeal to western sensibilities like Lil' Mac and Ridley or even characters MADE foreigners like Dark Samus, King K.Rool, Banjo & Kazooie and Steve makes me see Reimu as a very unlikely choice, because she represent something that Nintendo or Sakurai are no longer interesed in, using a character that really is only visible to Japanese audiences and niche western fans of Japanese media that is obscure worldwide and relies on underground fan products to keep itself afloat.
Can we get a fighter who appeals to Japanese tastes? Absolutely, but it likely will be someone who has at least some presence worldwide, NOT popularity, presence, as in "you don't need to translate the game yourself in order to play the game in your native language" presence, like Bandanna Dee or Sora (assuming Disney doesn't go into a fit) or Rex and so on.
This is another thing that bothers me.
When it comes to a spiritual anthetesis, Touhou and Nintendo don't seem to get along in general. Touhou relies on Fan Stuff, Doujin to be exact to recieve content, instead of "official" licensed stuff. Nintendo HATES anything fan-related to comes across them, and will destroy it at any cost, with only some glaring exceptions (Smash Flash 2, Mother 3 Fan Translation,) but those are the exceptions to the norm.
We have to remember that while Sakurai is the one making the characters, Nintendo also comes into play, beign the ones who requested Steve, and i don't see someone like Reimu crossing Nintendo's mind at all