@Tal45, well I suppose what would surprise one, may not surprise another. For example, you might be surprised that in this day and age I would be physically attacked for having a female partner or you might not be surprised at all, depending on your personal views and experiences I suppose.
@ODFOx, I suppose in terms of every day prejudices, it would be the "low level", perhaps unintentional, exclusion that people often don't realise they are doing. As an example, I have had a post man ask why it says Mrs and Mrs on a letter. I didn't feel they were meaning it in a hateful or homophobic way, more that they couldn't get their head around it and so pointed it out, in a, that must be a mistake kind of way. That or he was just a nosey arsehole.
With regards to why does my bisexuality matter, it matters in the same way your sexuality matters. If you are heterosexual, presumably you still identify as that, even if you are married/in a monogamous relationship. You don't become 'sexualityless' once you are in a committed relationship.
I made the point because people will often assume that I must be a lesbian because I have a wife (although I don't "look gay" 🙄) so if someone I don't know well, again, as an example said, 'oh have you seen Ryan Reynolds in his new movie? 😍......Oh sorry, he's obviously not up your street is he' , then I will explain that I'm bisexual, not because I'm offended, but simply to correct them.
@2020isnotbehaving, I think I've already answered that above. To answer your second question, no, not really, because that's just not who I am. Saying I'm bisexual isn't to signal that I could potentially be in a straight relationship again, more that that is just how I identify.