If I were a developer, I wouldn't trust Patreon not to crack down even more, especially on these games that changed everything to "roommates" and "landladies", but for which there are patches available or secret ways of restoring the incest content. The trend in general is for things to become more and more restrictive about things like that, and Patreon has already gone through at least two rounds of cracking down on games like that. I can't imagine that it's going to end there. Until there's a viable alternative to Patreon where developers of games like Big Brother can make their games without fear of suddenly being suspended or even banned, we're going to see more people moving completely away from incest.
Even with that belief, I still think DS was just tired of Big Brother, the incest genre in general, and really wanted to focus on Glamour. Patreon and other factors just made it a much easier decision to make to themselves and justify to their fans.