Oh yeah I am planning on sticking around and checking out the new version.
I get that, but it made a sense in a way. Twins separated at a young age, one goes with the father who ends up marrying the bimbo, and one goes with the mother who isn't married. The game would have actually allowed both fantasies since one son can seduce the new step bimbo, while the other could seduce his actual mother, I mean landladies.
By eliminating the twin angle, it will be interesting to see how it is changed. Also like I mentioned in my other post, having them swap places helps to deal with story issues of the MC not remembering basic details or simple conversations. It more easily explains why you as the player aren't familiar with the characters you interact with since you weren't raised with them. It also leads you down the path of who does or doesn't know.
You could keep the twins or make it a doppelganger story line but only make it playable around one MC. Then you have the MC dealing with both his regular family and the swapped family.
Or he could kinda just let you visit your father to seduce the bimbo and have you sent overseas by him on the past so you come back not knowing anyone