I'm also in the camp that wants to be able to romance/flirt with/shag (subject to an appropriate pursuit) the NPC of my choice, rather than being limited to those that the developers have chosen for me.
I don't look at the companions as all being pansexual, instead I think how lucky it is that the companion I chose to romance happens to share my sexuality (or, possibly, find me so irresistible that they act against their dominant sexuality...). I know that some of the others make 'leading' comments, but it is usually easy enough to shut such pre-flirtation conversation down.
I'd much rather have the 'problem' of shutting down overly friendly companions with whom I don't want a romantic relationship, than have the NPC with whom I feel my character would be attracted to happen to be unavailable because they are only interested in men/women/dwarfs/lizards,/whatever. It's MY game, after all, and I ought to have agency over who I can form relationships with.
