For what it's worth, my experiences in various Western Touhou communities have been that the populace generally wants older characters back more than they want new characters.
Really? What do you mean when you say people want old characters "back"? I mean, even for folks like Kaguya, Prismrivers, etc. who haven't made an in-game appearance in a long time, they haven't really gone anywhere. It's not like we could "get them back" somehow. They're still popular, all over fanworks and stuff.
From what I've seen (not that I'm very experienced with communities outside this one) people only seem to make that kind of complaint about PC-98 characters, and I think they still seem like a minority. It's probably more about wanting the characters to be more popular rather than actually wanting them to appear in a game, which is why you don't hear people screaming for someone like Rumia to return. She's popular despite not being in any new games, so nobody feels like she's vanished from the universe or whatever, while Mima, despite all the noise, is a relatively unpopular character. The complaining about Sakuya not being playable is probably more about a dislike of newer characters (Sanae in particular) than an actual love for Sakuya herself. And in any event you hear even less of that than you do the usual PC-98 complaining.
But in case, my point is that I'd find it very surprising if most people actually do want old characters to be recycled, rather than having new ones added. It's seems like a kind of bitter attitude to me, and I don't get the impression that the fandom is like that, at least in general. As I said, they're usually making a fuss about unpopular characters, and rabid fans of unpopular characters are almost by definition a minority.
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Also, many thanks to cuc for all the interesting info.