Though I dislike a lot of what the Touhou fandom does, in some ways I can't blame them and it's inevitable. The problem is that the two most popular games, EoSD and PCB don't actually feature very much dialogue. With Mima fandom obviously it's going to be even worse. People make their own assumptions as to what that character is like "Behind the scenes".
It's probably part of the reason ZUN did the Aya interviews. But something tells me it's still not enough. I think ZUN needs to write more short stories from the perspectives of the characters themselves, rather than the fairies or Rinnosuke so we can get a better idea how they think. What little dialogue we get in the games is often witty and inspiring. Some of it is generic anime/manga type shtick, but a lot of it is very nice. Compared to Curiosities of Lotus Asia for example though, it doesn't give a very complete or consistant view of the characters, and not everyone reads Curioisities of Lotus Asia, especially in western fandom.
Also, we remember characters for doing cool shit. Let's face it, Alice is a great character but how much cool shit does she do? Yes, doing stuff with dolls is pretty cool. But can you think of one awesome thing she's done with them exactly? In the games she just spams them around. In the comics and fictions she just sort of makes them.
What I've always wanted to see in Touhou was a greater sense of "epic". I hear SA which I've yet to play has more of a "sinister" feel which might help along these ends, more of a real threat. I think if we had a game where Keine threw herself in front of a ridiculous energy beam or some shit like that, people would learn to respect that character more and shed Womanly tears. On one hand the Touhou fandom is a little more "Hardcore" and less fluffy on some levels than for mainstream japanese media. But since he throws out the characters as near blank canvases you have to work hard to find out about, it negates this since it brings out the Kingdom Hearts Fangirl in everyone.
Of course you'll always get people like with the Final Fantasy fanbase, etc. that will abuse it, but they'll be an annex of the fandom, and more importantly, we won't need to fall back on fan works with a meatier storyline to begin with. But I think the Touhou fanbase is different to a lot of these other "Weeaboo" fandoms despite the overlap, in that the nature of the fandom is to fill in a lot of the blanks, as the meat of Touhou is scattered around between the games, short stories/books and comics, and debatedly in ZUN interviews and some other fan works too.
I know ZUN likes to "take it easy" with his games, but I do start to see a trend in both some of the PC98 games, and Mountain of Faith onwards where there's a sense of developing towards something.
The characters that are suggested at in Touhou games are just something special, the character design is absolutely top notch with tons of variety and we have all kinds of archetypes playing off another. That's why it's so popular. But I would think that while some people including perhaps ZUN himself would disagree, seeing a more story heavy game with a beginning, middle and end where things actually happen in it would really be a defining moment for Touhou, and it still has plenty of "Slice of Life" material to fall back on. Do more of both. More doujin writers actually need to come to ZUN and ask him for advice, it seems only respectful to me. That way we get more "official" stuff and all ZUN has to do is flick through it and correct a couple of things.
Put more story in the games. Put more of a sense of danger in the games. Put Rinnosuke in the games, why not, he's a great character, maybe a few more males too - again this is a huge part of why people do not take Touhou seriously, even though it's not it comes off as a silly lolicon, harem or yuri type affair.
Everytime I play a Touhou game, I get really riled up by the huge attacks and FUCK YES music. But at the end of the day, it doesn't quite go where it feels like it should and I think that is part of what results in a lot of the directionless, misrepresentative fiction.
Touhou is like the really awesome but shy goth girl in the corner who gets all dressed up and ready to make an impression but just ends up going home and drinking Tea listening to the Smiths moping that everyone thinks she's a lesbian. It needs more confidence as a series for people to take it series, and thought ZUN might not like that, it's probably the best way to "protect" his characters and ideas. A lot of people say the dude that does Higurashi does doujin stuff that's more "epic" in nature, but I just don't find the character designs etc. fit it quite as well as Touhou could.
If not ZUN, someone really should honour the ideas I've presented here and clear it by him.