I can understand if some people like Zoe, to me she just seems pointless as Ellie could've very well been the "best friend" of Megan and help to push her buttons the same way Zoe is doing. Hell, that would've made much more sense than the current "I'm the new girl in the school, wanna fuck my ass on my first day here? Or meet my mom on my second day?" lore that Ellie has. I agree that some games either suffer from not having enough characters, but then I also think that it is most of the times result of bad and lazy writing. Example can be used with Inceton's other game, the first Summer with Mia where there is (as far as I remember) only three main girls that the main character is banging through the game, and yet the game is able to carry on very well for a good length because of it's writing. As you mentioned, now in this one we have the concept that really would give the main character free hands to try almost everything you could possibly imagine him to do with the girls, yet the game fails to deliver and utilise that concept because there is too many characters and too much happening at the same time so basically there is no way to tie it up together properly. And this same thing is also happening in Summer with Mia 2, where there is too many characters and not enough time for everyone. For some reason for these newest ones they just don't seem to find the balance, and that's really restraining them from hitting the home runs with them.
I do also agree 100% that adding more non-incestual love interests in a heavy incest game from the team called INCEsTON at the middle of the game is kinda interesting twist. Leaving out some of the cast mentioned before, they still would've had the non-incestual love interests in Ellie and Nicole, which would've still given something for everyone, meaning the people who don't care too much about the incest stuff. What I see as a problem here is that it seems like they didn't properly think about what they were doing when adding those extra characters in. Like you said, it took time off from the main girls, and in my opinion really hurt the flow of the story. Not knowing what content the two last episodes will have inside of them, but to me it feels kinda lame that there most likely is going to be only one or two proper solo sex scene with each of the girls. Elizabeth is already covered, Jess had her one-on-one scene in the garage, Megan's first proper solo scene most likely was the latest one in Amy's house (which was once again drunk sex, yay...), Ellie had her own solo scene at the party in that "sex dungeon", Nicole just had her scene in the school, Zoe got railed on the hood of the car, Sophie got hers in the sex swing and Amy got hers too in the party. From the side cast, Chloe got hers as did Ellie's mom also. All that build up for such a small reward in the end, as now all there is left to cover is the main reasons why the day repeats, what will go down in the end of the day and such things before wrapping it up. It really gives the vibes that when adding Amy and Angel in the game, they had different plans for Season 3, but then they just got fed up to the current concept and decided to change things up for Season 3, as why the whole thing now feels off-paced and weird when they are suddenly turning the heat up to maximum and then just shutting it down completely.