Interesting thread, interesting comments.
First, my take on the list:
Wonder Woman: I could see it either way.
Hercules: I could see it either way, if you wanted to play up the aspect of hedonism in ancient Greece.
Catman: Not from the stories I've read by Gail Simone.
Shrinking Violet and Lightning Lass: Have clearly been in a relationship for years, in the original Legion's timeline.
Steel Sterling: Come on, man. Even I, who have or have read tens of thousands of comic books over 30-plus years, am like, "WTF? Who's tracking that one?"
Storm: I absolutely could've seen this before she got married.
Harley Quinn and Poison Ivy: I could see Pamela Isley, not sure on Quinn. Are we saying that The Joker never tapped that because they're both crazy as hell?
Gambit: That's ridiculous. The guy's chased Rogue for 25 years now.
Tim Drake: For most of his existence, he was pretty much a pre-teen kid. I think it's a little ridiculous for anyone to pretend like, either way, that they have a feel for that with this character. What, was he supposed to have gotten engaged at 12?
Captain America: Oh, for fuck's sake. That's so ridiculous, it doesn't bear repeating, and was clearly dropped in just to make people talk. The Carters. Diamondback. Steve Rogers simply doesn't date a ton, because he's old-fashioned.
As for some of the arguments in the thread, my take is this: It's 2012. Kate Kane's creation didn't blow up the internet. Neither did Shrinking Violet and Lightning Lass' outing in the mid-80s. But here's the bottom line: That shouldn't be done with characters that have clearly established sexual orientation. If it's ambiguous, then fine.
Again: You could do it with Wonder Woman and I wouldn't blink, because for the majority of her existence, she wasn't with anyone. Depending on how the story was told, it could make a lot of sense.
But at the same time, you can't do it with Gambit. Because that doesn't pass the smell test. Again, the guy has chased Rogue for TWENTY-FIVE YEARS, through numerous books, from numerous writers. You can't just ignore that just for the hell of it -- that's bad writing. If you never had Gambit doing it, then fine. But you can't flip that switch on and off -- it's not that it's unfair to readers. It's unfair to the cause, of gays/lesbians, to do that. It doesn't advance the normalization and portrayal of characters to say that, out of the blue, Gambit's gay.
Create new characters, like Kate Kane. If you find established characters who have never really been portrayed one way or the other and it makes sense, then that's fine, too.
*Sniff, sniff* "Damn it, Diana...If I'd known they would trade us in for a JT Krul-written Captain Atom and "The Savage Hawkman," I'd have let Superboy-Prime destroy all reality.""Superman flies and is really strong...what the fuck else do you need to know?!"
-- Hitler, expressing his displeasure about DC rebooting and complaints about continuity