It's not rely all in the writers but the popular platforms that are used to public to attract potential contribution, there are plenty games affected by their politics. Just think of it, this game wasn't approve on Steam just because Chiaki appears in it and have 12yr old. An example more obvious to you would be RE2-3R, Raccoon City, where there is a character Emma Kendo that originally will be describe as a 10yr old lil girl infected by T-Virus, that description never got into final release. Other example more visceral was in RE:OF2 where there is a data inside the game of a kid zombie that will appear in an scenario with the possibility to the players to be shoot it. Nowadays, many platforms and companies are avoiding as possible any form of controversy to be safe from legal issues, specially in "Occident", even if Original Chiaki will be never intended to be lewdable, the tone of how was describe her circumstances could implied for the testers something different, the same happen with MC living with Yasuka and Noriko,
RNGeusEX intended a more obvious incest story there but for how much he wants he can't, the same happened with SS of DarkCookie, he still develop content that appoints without a doubt how much MC and the girls who he lives are family but as the original story is made he can't. And, there isn't much a writer can do to fix it without remaking the story and therefore the relations between characters as the reasons behind all that as well in a way to be understood reasonable without doubts.