I agree with a lot of what Mikka said on page 1. Everyone being bisexual works in some games, but might not be a good fit for Academagia.
Anyway, what I came into this ancient thread to say is that I'd love gay/bi romance options, either official ones or via mods. But even if there aren't any official ones I'd really like some NPC's to be officially non-straight. You wouldn't even have to make a big deal out of it, just putting it there so that some players would notice would be enough for me. Just to acknowledge that, you know, non-straight people exist. You've got all these actions to influence members of the opposite sex, as well as being able to spend background points on being popular with the opposite sex, and there are some characters whose profiles only describe how popular they are with the boys/girls. When the game mechanics aren't also acknowledging that non-straight people exist, this kind of sends the wrong message.
I find Academagia to be a very realistic depiction of a school. Realistic, but depressing. There are a lot of romance-related rumours and intrigue, being popular with the opposite sex is an important coolness factor, there's a lot of bullying going on and, as far as we know, no student or teacher is non-straight. I can understand why no one would want to be open about their sexuality in a school like that. (The students don't use homophobic slurs, though, so I guess in that respect it is better than reality.) Having a few NPCs that aren't straight (at least so that it's notable in the game mechanics or is mentioned briefly somewhere) might improve the school atmosphere.
I don't mean to sound like this is the single most important thing to be changed and that if you don't change it the game series will be terrible. All in all, I think Academagia is a school full of wonder and magic and excitement. I'd love to go there. This one aspect of Academagia just happens to bother me.