I can't say for sure, but for me it looks like maybe the first concept wasn't as big as it is now, but then money flow from brand new characters and their paths started affecting the development process. While already being wide, game does not center much on any of characters, chosing quantity over quality. That's why among... I dunno... 30 characters, only few have extended branches of their stories, while others are linear, changing course only to make an intro for more new characters.
Not to "erm ackshully" you, but I think there are only (well, "only") 17 girls with routes right now. There are 8 guardians total, no extra girls in Viridice or Lycalis, only Bev as an extra in Keisama or however you spell it, fuckin'
four extras in Hornsperia, Kendra, Nyxmay, Makla, and Vai'klis, then Shiena, Margarita, Kive, and Croix. That number will go up to 21 though, guaranteed with girls we know will get routes including Meido Twins, Helga (hopefully), the Queen, and finally Synala- who will definitely have more girls as part of her route of course, but we don't know who or how many.
Writing that out, it's kinda crazy that Viridice and Lycalis are so stunted in the routes department, and also that Hornsperia has so many. Wildly imbalanced, and it might be even more so if that cutie succ ends up with a route.