While I agree with your post people like us are in the minority and most people are that play these games want to fuck everyone and don't actually care about the story and mainly play for the sex scenes that's just fact and there isn't really anything you can do to change that harem is just more popular.
If there is a choice between a game where the MC has a harem of several women all waiting on their turn to fuck him or a realistic,touching and engaging story with solo romances the vast majority of people playing these games are going to prefer the harem every time since to them Harem=more sex scenes.
Just look at the most popular adult games on patreon and apart from Being a DIK and City of Broken Dreamers they are all harem games or games where you can go around fucking every character with no consequences.
Not saying you're wrong or that the game must have a unique route.
But look over the side of a harem route is optional. Like, you just like an LI, ok. You just follow her. You are interested in more than one LI, ok too. And so on.
Just because I like a Harem route doesn't mean I want a big orgy at the end. It's just that I want to enjoy the game and what it has to offer 100% in one play. No thousands of saves, or starting all over again.
I don't see a problem for a game that has a harem route, since we can also follow a solo route, which is most of the time optional, so I don't see a problem having a harem route at all. It's not realistic. But dammit, it's a game to enjoy our fetishes that we can't get in real life.
What I mean is, if you have a harem route and several solo routes, one for each girl. I think everyone can have fun with their tastes and preferences. You don't want to serve several girls, well, it's your preference. Is not having the harem route a problem now? yes, it prevents people who want to serve more than one LI from having the most fun.
But each one with his opinion. That said I don't expect every game in the world to follow and have my wishes. But it would be great if all things are optional.