What a long but passionate answer! And I have to agree with all your points because that's just how I felt after I spend 20+ hours on the game, trying to find a good solution.
I'm the usual Otome player but I didn't expect this game to be typical sweet and soft, I prepared myself for a hell ride and twisted romance, I read the warnings and everything. I simply liked the concept and the promised content, intrigued by the demo and updates but never did I expect a gut punch like this. Playing through all routes and endings only to be told that nothing mattered and enduring so much emotional pain without any relief. I had one guilt trip after another and even felt so bad romancing the dudes that I just became friends with them only to realize that the ending is technically the same. Players felt bad playing the game. Players felt like they played the game wrong. Players had a therapy trauma session on the freaking game server.
Even a kickstarter sponsor and beta tester regretted their choice to support this project. On Steam the game already has a rating of 6/10, many raising the same concern and bitterness about the endings and the outcomes. Some theorized it's for shock value and to pull a sneaky on the players instead, well, congratualtions, you got your reactions devs, but I will be honest - you shot yourselves in the legs. Many potential customers and fans now turning away or regretting their purchase, even swearing to never buy a game from you again. And the people of tomorrow will read the reviews and comments, immediately turning away and thus losing all the money invested into it. How did this even turn out like this? The prequel is even happier and that is BL only, how did this following one turn out so frustrating? Many expectations crushed, not only from Otome players buy also those who enjoy psychological horror - where is the dark comedy in this? It ends up in a tragedy anyway, labeling it as Drama isn't the same thing. Optional romance - It says that but really, you will feel uncomfortable and awkward, not in the funny way.
So many bad endings, making you responsible for deaths and destruction, suicide and homicide and then you only get a lazy mindf*ck of an ending. A new experience and not for anyone, I get it, but what kind of niche masochists are you looking for? In the end even the masochists want a satisfying, even if not good, end. Sometimes being experimental is not always good, especially because how the game was marketed. As if lead astray after waiting so long for it, not for the romance only but the influence you were promised to have in it. This is basically a linear VN where only the last choices really matter, a story you could have told in a Kinetic VN with a set MC. I mean, to get the special endings you have to be the same house as your mentor - so much for being anything you want.
The only way they can save this is to add better endings, step up the optional romance and/ or make the choices really worth their impact. Many already ask for a DLC to fix this or to get more information and closure about the events afterwards.
Heck, I even investigated on the hidden meanings in the BGs, CGs and ending titles!
I really don't want to stop anyone from playing it, it was in a sense still an unique experience and story with great assets - from the art, the backgrounds, the music and the writing but I wouldn't give this more than a 7.5/10 because of this major flaw.