Okay, so after this it probably needs to be said that I do recognize everyone's right to interpret fictional characters however they like. And in the case of Sherlock Holmes it's definitely justified since Doyle did once say it was okay to go ahead and get him killed or married or whatever. So yeah, you have the right to interpret him as gay, straight or anything else. And I have the right to interpret him as ace.
(I have to admit though, that in some cases a small voice inside me does ask: Do you absolutely have to? If the original Sherlock Holmes says he's never been in love, is it really necessary to figure that it must mean pretty much anything else except what he says? Yes, as an aromantic asexual I am biased, because that narrative is far too familiar to me from real life. But maybe that's partially why I find him a good representative. No matter what he says in the stories, people will think it's not the truth. That being said, I repeat: You have the right to do it. I just don't have to like it.)
Naturally, I'm not saying that Moffat is doing anything wrong with interpreting him as straight. It just bugs me that he claims the reason for that is that an asexual character wouldn't be interesting enough. Come on, that's the dumbest reason I've ever heard! It only sounds to me that Moffat doesn't have enough imagination. Or know anything about asexuals. Asexuals not having those (apparently essentially so much more complicated) motives that non-aces do is just an excuse. And I only want to say two things. One: It's okay not to have an excuse. Everyone can do what they want and ideas don't always have to be that rational. Two: Asexuals are every bit as complicated and interesting as anyone else. Even when it's about sex and relationships. If you don't get it, it's not really that hard to find out.
That aside, I think The Abominable Bride was a good episode. Even if the series could've done without it, I think it's something the fandom definitely needed. Because it can give such nostalgic feels to all long-time sherlockians and it can bring the newer ones, who aren't familiar with the original, a step closer to where this all is coming from. The old and the new are mixed in it in a way they never have been before. I think it's been done really well, there's definitely a huge amount of thought behind it. There's so carefully crafted interaction between so many versions of Sherlock. I need to see it again to dwell on the details. And yet it never fails to be meaningful for the new series as well.
Hardly anyone of the characters of Sherlock is what I understand the original ones to be like, but even so, I can't wait for the next season.