That's sort of why I was pissed when JK was like "OH BTW" about Dumbledore, after the fact. :T Like, a person's sexuality is not who they are. And being open with it is not always a necessity, either. It's whatever they want to do, or whatever they're comfortable with. And for many individuals, coming out can be scary. So, while it's realistic that in some series it might take a bit for them to do so - it's foolish to have it be a standard. Not everyone's going to have that "fear of God" in them, or be faced with pre-existing bullies, etc.
It completely depends!

But when it comes to fiction, usually there would be heavy hints, even with a secondary character... IDK, I just thought that was a "safe" move on her part. There was *zero* reason for her to wait so long, imho. :( And I don't think I would have been as encouraged to roll my eyes if it had been let out in an earlier interview. Like, around the fifth book - OH BTW than :T Argh. I hate to nitpick, but that was super disappointing.