Look, it's fine that the MC is the only guy, that's good. What's not good is how you've developed the LIs. If you wanted to create a group of LIs who would be unappealing to harem fans, you've nailed it. The childhood friend who posts nude photos online and asks the MC to take pictures of themselves having sex so she can upload them to her account is a wonderful way to waste a LI. The succubus femdom/rape scene is disastrous considering most harem fans hate femdom. And having an LI tell the MC that she needs to eat semen to maintain her human form isn't going to make her appealing (what will happen is that the average fan will ask questions they don't want to ask, and the answer to which is something that doesn't reflect well on said LI).
One recommendation is that it's best to know as little as possible about the LI's sexual past. And fetishes, it's best if they discover them with the MC (as long as the fetish isn't being a porn actress, as is the case with the childhood friend, then it's best not to experiment with it at all).
I actually don't think it's difficult to modify the dialogue to make the LIs more appealing. For example, the succubus could convince the MC to have sex (you could even make her a virgin because, well, a normal succubus isn't going to be very popular with harem fans due to her more than questionable past; removing the possibility of said past by making her a virgin will make her more appealing). As for the one who needs semen to maintain her human form, this only create some umpleasant questions (how has she maintained her human form for years? Guess what you're thinking... Exactly what you're thinking), so it's better to modify this and use something that avoid that scenario. The childhood friend who posts nude photos and wants to use the MC to make porn... there's no solution unless you completely change her story.