Touhou's real status does not matter.
Smash makes the status.
That's what really matters.
Sorry... excuse me? Real status doesn't matter? I mean, put Reimu aside for a second; status determines which characters get in. Their popularity, prevalence, impact, recency... that's status. Real status is everything that matters.
Why do you think we got Sonic, Mega Man, Pac-Man, Ryu, Cloud, Hero, Steve, etc. instead of Ristar, Spencer, Mappy, Ryo Sakazaki, Vaan, Manjimaru, and, idk, Alien Hominid? Luck? Or is it due to the former group being among the highest status characters in the medium.
Smash makes the status? No. Smash makes inclusions based on the status. The Smash fanbase makes assumptions, based on the inclusions/exclusions. Status exists free from Smash, because characters exist free from Smash. If the only status that matters is the one the Smash fanbase concocts only once a character gets in, then characters like Master Chief and Blinx the Cat currently have the same gaming-wide status. That's absurd.
Do you think they'll go, "should we add Master Chief?" "Nah, status doesn't matter, go with Blinx, he'll be cheaper."
Status is crucial. The real status. The Smash status is just reactionary.
If Reimu gets in, then Touhou's popularity in Japan and other Asian countries will be used as the reason for her inclusion within the community.
If Reimu doesn't get in, then Touhou's obscurity in the Western countries will be used as the reason for her exclusion within the community.
Either way, the outcome determines the reason.
That will be the de facto truth eventually within the smash community.
Well... yeah, no ****.
If Crash gets in his popularity/prevalence will be used as the reason for his inclusion within the community.
If Crash doesn't get in, then being western and Activision shenanigans will be used as the reason for his exclusion within the community.
This isn't preemptive speculation, it's retrospective analysis. And we'll do that for Reimu and Crash and everyone in due course.
So the question should be, does Nintendo want the Touhou franchise to become more mainstream and Nintendo-centric or not.
Is that the question? Because that's not been the motivation behind adding any of the other third-parties. Other than maybe Bayo, who is in a very different situation. They add them because of who they or their series are, and potentially the fans, and therefore money, they can bring.
I don't think Nintendo had any illusions that adding Cloud or Ryu was gonna get future mainline FF or SF games on their systems.