I think it's really interesting to get to see how people on the production side of manga view things. That being said, this discussion passed over what I think is probably the most important part of the growing popularity of yuri: society is more accepting.
Now, don't get me wrong. A large part of the appeal still comes from the (male) audience perspective that glorifies pure, innocent schoolgirl flirting; or, obversely, just appreciates lesbian porn. But at the same time, the diversity of the kinds of yuri stories being told has been increasing dramatically. Authors are telling cute, fluffy romance stories, serious adult dramas, and supernatural or sci-fi stories with yuri as a focus.
Moreover, I feel that, in yuri works generally, the fact that the romance is between girls is becoming less and less of a creative conceit or marketing bait, but simply a fact of the stories themselves. I think that, as opposed to previous years, people are able to create characters that feel like they are in genuine relationships. For instance, Bloom Into You could just as easily be a het romance about how Yu has difficulty understanding that she's in love with a guy. But it isn't - and at the same time, the characters' genders inform how they act and feel in a realistic way.
I'm not saying that all yuri stories should be interchangeable with het stories. I'm just saying that I'm glad that yuri stories are becoming more humanized, if that makes sense. That's not due to any particular fandom interests, that's a shift that I think has resulted from society's evolving views on homosexuality.