That's because most videogames live or die on their gameplay alone, and anything else is only occasionally more than a bonus. The exceptions? Well, RP Gs
: Plenty of people will gush about the plot, music and visuals in an RPG while being mostly neutral to the gameplay (or even griping about it). Also, I've seen people who love Metal Gear Solid's mindfuck plot diss its gameplay (and visa versa; in this case it's hard to really say which is the core). And lord knows there's people who love everything about Silent Hill except the parts where you have to deal with actual gameplay. You won't find people calling themselves fans of Megaman while disliking the shooting, no, but that's because shooting stuff is its only real draw, as it is with a lot of games. Games that have other features which are at least as much of a draw as the gameplay, like plot or atmosphere, sometimes have fans who are fans of that more than they are fans of the gameplay.
The only difference with Touhou is that even though the gameplay is top-notch (unlike, say, most survival horror games and many RP Gs
), it's in a genre which is fairly inaccessible to many people; only a certain type of player can ever complete one of Zun's games on normal, including "can stick with the thing long enough to finish without getting fed up" in my definition of "can complete". Most anybody who wants to see that plot can slog through Final Fantasy with enough grinding, but not everybody who would be interested in the plot, fandom, etc. can complete a Touhou game. Or would find it fun.
Speaking of this, I have definitely seriously considered buying SWR, and still may do so sometime. Unlike the others (to me), SWR looks fuuuuuuuun
. Mostly I haven't because I'd have to navigate a lot of Japanese crap to do so, and I'm not sure if it'd work on Vista. And, you know, because there's always more things I "ought" to try than I can actually buy.