Because it's 2020 and we're supposed to challenge norms.
So you'd rather force your own quota onto the game's creator to have them make more female LIs against their own will (which would most likely lead to neglected characters) instead of looking for other specific games that willingly focus on female LIs, and then support their creators in order to have more content like that?
You're really pressed about someone's opinion that doesn't effect you. You realize not everyone is just gay or straight, right? Having one LI is limiting because it's a situation of, "you're not entirely straight? Date the one gay person in town!" It's a start but it could be better. I'm not forcing anything on the devs but the comment sections on itch exist for this purpose and if you disagree with me that's fine. Move tf on.
"It's fine" but at the same time you feel the need to express yourself in an agressive way, you want to voice your opinion but you don't want to let others do the same thing? The way you phrased it, that "we're supposed to" do it, does have a forced vibe to it. I never said bisexual people don't exist, and there's a market for that as well. But this isn't real life, it's just a game and games have target audiences. Being upset about there being only a sort of bonus female LI in an otome mainly targeted towards a straight female audience (that potential bisexual players, or merely people who like yuri might enjoy) is kind of like being upset about an open-world game not having enough mini-games within it. Now, I might be wrong, maybe the creator of the game did want to primarily attract a bisexual audience, in which case yes, the game isn't very balanced. But hey, it doesn't seem to be the case here.