To be honest, I have literally no opinion on male characters introduced to Touhou, but seeing how strongly a lot of people feel about it, I was curious to see if there was a common thread. And yeah, seems to essentially boil down to what Stuffman said about the game's "feminine aesthetic", which is a good way to put it.
And truly, how would Rinnosuke deal with another man in Gensokyo? It'd be awkward, certainly. And not in a zany, episode-of-Friends kinda way, either.