Blackwall is a very divisive character, for reasons you'll find out on your own (do avoid reading spoilers), and people tend to get heated up discussing him. We don't bring him up much in the thread anymore because every time it was done before it turned into a barrage of "372932591 reasons why I hate Blackwall" versus me and the other three or four of his fans we have here going "can we please not turn this into a Blackwall hate thread?"
Like Tish said, the contentiousness is why we largely avoid the subject these days. This thread generally tries to avoid character hate of all sorts. Sebastian, Anders, Blackwall... it's better we all just agree to disagree about these more controversial characters, and continue agreeing that our Cullen-Wullen is the bee's knees.
But I do love Blackwall, his romance is my second favorite in the game, and I do recommend giving it a try with another character at some point. He can be very wrong for certain Inquisitors, but he can also be a very good romance for the right kind of character.
My third favorite romance is Sera, who also doesn't get discussed a lot here... I guess because we just don't have a very large number of F/F fans? It happens, people tend to flock certain ways. More people here tend to like Solas romance, which did nothing for me - Sera's, on the other hand, is adorable and heartbreaking in just the right way for my tastes. I've romanced her with two different characters now, and resisting her has become the same struggle I have with resisting Blackwall's charms. Not flirting with them is haaard.
Well, I'd like to point out that I'm not a Blackwall hater, just have problems with how his romance is done, and I respect that we have different opinions on my particular objection.
I actually have no particular opinion on Sebastian and Anders as it happens either, I just find neither attractive, but I can see the appeal to others. I actually liked DAA Anders, but Anders-Justice does nothing for me. What puts me off Sebastian isn't the same thing I hear other people state (you can PM me if you really want to know, it isn't actually that negative, but no reason to start that discussion on the forum).
Actually, I'm not sure that Sera's lack of popularity has anything to do with f/f fans. I adored Isabella in a f/f romance, and I'd have loved for Morrigan and Cassandra to be f/f romanceable. Of the four romances available to my dwarven females, hers is the only one I moderately like as written (just not nearly as much as all four romances my dwarves are gated from). Her brand of nuttiness is a bit over the top for me at times, and some of the things she says put me off and leaves me lukewarm on her as an LI, and I suspect that's what puts some people off.