You're assuming a lot of things with this post.
1) That we're only going to have 6 romances.
2) The sexuality of those characters you mentioned. Iron Bull is not 100% confirmed (as bisexual or as a romance, same with Scribbles) and none of the others on your list have had their sexuality confirmed either.
3) That there is a problem with sharing bisexual LIs.
I'm sure you'll have a couple of straight lady LIs to choose from. Okay, that's probably at least two right there. Guess what? If Cassandra is bisexual, you'd be able to romance her. If Vivienne (which I noticed you left out) is bi, again, you'd be able to romance her. Same goes with any bisexual lady LI, unless that's somehow bad to you. Having these characters bisexual isn't excluding you. I loathe to use the word "privilege," but this is a textbook case.
Equal does not mean less. And we still aren't equal yet. Most of the gaming industry is still trying to bang down your door. It must be nice because many of us can't even imagine that. Now you're saying it's "unfair" if the one company that truly gives a crap about the LGBTQ gamer community might make a few ladies bisexual. Do you have any idea how immature you sound, not to mention a little homophobic?
I personally don't understand why it's such a huge deal that maybe...just maybe...straight men might only have two options all to themselves and might have to share the bisexual LIs with the LGBT community. Also, perhaps it's time to realize that BioWare doesn't care if they make a few straight male gamers unhappy. I cannot stress this enough: (nearly) equal for the minority doesn't mean less for the majority. I'm very thankful that most of the straight men have been supportive and happy for the LGBTQ community. Many of them certainly don't mind if their preferred female LI is bisexual either. It doesn't affect their game, so why should it?
Welcome to the 21st Century. If you think you're still going to get all of the favoritism that you'd gotten in the last 20+ years, then you're sadly mistaken. Time to learn how to share with others.