Chris Perkins talked about this a bit in that Q n A where he hinted at Ravenloft. It was linked here like 2 months back or so.
It was basically what everyone else here said. The smaller books don't look good on a shelf for the stores. Many DMs who want to buy books, just want to run from one published adventure to the next, which is easier with a longer adventure. And the margins on books in general mean that Wizards don't want to release a lot of books. They think that the market just will not sustain them releasing 10 books a month, that people buy, but do not use. That's why I imagine they're leaning on UA and DM's Guild.
I'm someone who likes to do my own homebrew stuff, and occasionally tossing in some shorter polished published stuff. Something I can drop into a pre existing campaign for a few weeks, and then move on. Mix it up, see stuff that's different from my own personal narrative meta I suppose. I have no interest in running published stuff for months and years at a time, but that also apparently means I'm not the target demo of published adventures.
It was basically what everyone else here said. The smaller books don't look good on a shelf for the stores. Many DMs who want to buy books, just want to run from one published adventure to the next, which is easier with a longer adventure. And the margins on books in general mean that Wizards don't want to release a lot of books. They think that the market just will not sustain them releasing 10 books a month, that people buy, but do not use. That's why I imagine they're leaning on UA and DM's Guild.
I'm someone who likes to do my own homebrew stuff, and occasionally tossing in some shorter polished published stuff. Something I can drop into a pre existing campaign for a few weeks, and then move on. Mix it up, see stuff that's different from my own personal narrative meta I suppose. I have no interest in running published stuff for months and years at a time, but that also apparently means I'm not the target demo of published adventures.