Why do you think they cover Dragonball, Pokemon, and Ghibli stuff? Why do you think they (geek/mainstream media) wouldn't want a stake in an industry that the OP argues is highly profitable? The OP's article asks why LootCrate doesn't have anime stuff. It'd certainly sell. Why do you think there's a divide between the worlds? Why does AX get no coverage while Comiccon does? How did Comiccon break through? We're not just talking about Wil Wheaton here, we're talking about big, mainstream outlets too.
Pokemon, Dragon Ball, and Ghibli are pretty unique examples that have history behind them that allowed them to break into mainstream mind share. I personally think it's pretty clear why those are still covered while other stuff isn't.
As for the other stuff, I can only speculate. Might be easier to discuss it with examples in mind but there could be any number of reasons. The simplest, to me, is that the folks that write just aren't interested. It makes way more sense than anything.
For anime goods, that's way tougher than you think. For one most of it is produced in Japan meaning there are supplier and import stuff to deal with regularly for most US businesses. If they wanted to make their own goods to sell, then they'd still need to deal with Japan the owner's of the properties are there. That's not an easy thing for a small US retailer.
If the explanation is as simple as the fact that Marvel has made movies and anime hasn't, then fair enough--although one wonders why Marvel was able to break through and anime wasn't. Marvel breaking through was enabled by the routinization of CG starting around Spiderman becoming big. The technology is there to make a big budget anime or a live action adaptation of an anime brand. Attempts to do so have largely alienated the core anime audience (for being inauthentic) and not gained the western audience they were chasing.
I don't think you need to wonder why Marvel was able to break through. For one, they're a company that is primarily here in the US. It's just much easier for them to do work here. Most of the companies release anime here in the US are folks that just license it from the anime companies and that's usually just the show itself and not goods.
Marvel has also decades of working on movies and television to figure out how to make their stuff popular. It's not like they suddenly hit success out of the blue. They had a lot of attempts over the years, many that were terrible, to get to this point.
As for anime films, I don't think many can ever get the budget that those superhero movies could get so producing a film of similar quality would be pretty difficult. Then there aren't that many people in Hollywood that understand anime well enough to create a movie that both captures the core audience and makes inroads with new viewers. As I said above, it took a long time for Marvel to do so.
If the only issue is that geek writers don't know enough about anime, what's stopping them from learning? Do you think it's just a matter of time, where Chris Hardwick will post about Azumanga Daioh and then problem solved? I dunno man. If he doesn't know about it, I don't think it's a coincidence, I think it's something structured about how the public face of the content and the community is hostile.
They might not be interested? That's the only thing stopping a geek writer from learning. A writer just learning about anime now has all kinds of content to pull from, from all decades, to learn what it's about. There's enough content put out nowadays that is very good even when you factor out the smut.
I guess they could also continue growing their site by focusing on their current readership as well. If it ain't broken, there's no need to fix it and all that.
I just don't buy the argument that it's mostly a content and community issue. The smut issue with anime, which is slightly different than the pandering issue I've talked about in the past, is only relatively recent. I'd say the last 4-6 years or so? It's very new overall. That I can sort of see in the current climate but go back a few years and that reasoning kinda goes poof.