Yeah I wonder how that's gonna make them "fleshed out" more? Are they actually going to come with backstories on how their sexualities have shaped their lives?
Hmm yeah sorry Natashina, guess you and your friends aren't REALISTIC!

Isn't sexuality largely a non-issue throughout most of Thedas? The ONLY way I can see this having any significance is for gay/lesbian elves or nobles, so either Cass, Sera, or Solas, and it's unlikely to be Cass given her announcement as an LI already.
Honestly, the most 'fleshing out' I'm anticipating is a throw-away line, and nothing that couldn't be accomplished by them being bi and having previously had an s/s relationship. But that's ignoring writer discretion, and I do have to respect that as a writer who likes having ownership over the characters I write, if not necessarily as a player.