Ranranrun said: Your logic doesn't work in Gensokyo. In Gensokyo, the clothes are in the genes.
This might actually be true, surprisingly enough. How else do you explain all the wild youkai and fairies to have fancy dresses despite being homeless and having no money? A possible explanation is that the dresses of the Touhous are indeed part of their bodies. And when a youkai grows in power, so do their clothing become more fancier (explaining all those fancy dressed ex-stage versions of the girls too). It also explains why some of the dresses look so much like the creature the youkai originally was (Wriggle, Yamame).