FRACTAL HATS!
Frats?
In any case, regarding the discussion about returning characters...I'd actually rather not see old characters return as NPCs in the main games. The main games have always been there to introduce a new batch of characters into the series, and to have an old character return to fill in a slot a new character could have occupied feels kind of like we're being gypped at this point. That's what the decimal games are for; sometimes they'll add a new character or two (Suika, Tenshi, Iku, Hatate), but most of the cast will be returning characters who get their backgrounds fleshed out a bit more.
In addition, some characters not being as fleshed out as others will, for better or worse, just give the fandom more freedom to make their own interpretations of a character. Using Flandre as an example (only because she's one of my favorite characters and I've talked about bringing her back before), it's entirely possible my interpretation of her would be completely contrary to what ZUN imagined and, being the strict canon-follower I am, I'd have to drop or at the very least change my interpretation of her to suit ZUN's new information.
tl;dr, main games are for adding new characters, and the fans/decimal games/print works can flesh out the rest.