If you're like me (you're not hyper-sensitive to NTR) you can view these scenes without thinking much about it.
Your opinion on it all is your opinion, and that is fine, but
So long as you understand what a succubus is it shouldn't phase you, basically.
Saying "it shouldn't phase you" is like telling someone what should phase them is a circler argument.
If I bought a sex slave should I not mined if she has sex with others without my say so. She is a sex slave sex is what she does. There is nothing stating that the MC is not providing enough for her, even said one off scene pretty much reaffirms that. Now If it doesn't bother you more power to you, but the scene adds nothing to the story as you said.
MC's dick is her ideal dick. Well she remolded it in the first place. No natural born man can compare. Anyone can see that a mile away. Normal men do not provide as much energy. I'm sure that was the main reason the MC was picked in the first place.
Should it have been removed? I myself said "no just make it optional" along with the other "controversial" scene. Don't know what happened outside of f95 besides it was a shit show, but dev decided to remove them and make them password protected patrion version only content. He also has not been active in the form AFAIK since.
Is it NTR or not? That is one of the conversations that get your post deleted so I will avoid it.
futa shenanigans later and is only NTR if you have very thin skin when it comes to that (which is understandable).
That is nothing but insulting. Just because you do not like something and it bothers you more then someone else those not mean you have a thin skin. If you dislike lesbian, futa, and, or sharing you will not like that scene. Making it the MCs dick will not make everyone suddenly think it is OK, or not another girl fucking your girlfriend with a dick. I will not play a game with scat that is not avoidable. Those that mean my skin is thin. No it just means I do not like scat. I avoid playing games with mutilation. Is my skin thin no I just do not like it. I don't like the taste of brussel sprouts etc.
If my or anyone else kink is to be the only man that fucks everyone that is my kink don't try to shame me, or anyone else about it.
Not being bothered about it is fine, but to say others or wrong by being bothered about it goes beyond just "giving your opinion". Harassing, and or attacking the dev is wrong too. I'm not saying I agree with such behaver. Not liking what happened and stating your opinion is fine and all that but things went to far.