I'm not too bothered, as I think the film is massively overhyped, but it is a shame. It never really stood a chance, anime fans brought into the hype of themselves and BBC News Magazine.
The highest grossing anime of all time still hasn't grossed that much more than some US CG films' budgets. (It's currently around $332m.) It's still only been given a limited release in the UK and only an Oscar qualifying run in the US. Nobody will have seen it, especially since they refused to authorise screeners. I highly suspect more Americans will have seen the film aboard a plane than they did in US Cinemas thus far (and that takes some effort, as it's title on Emirates is "Japanese - Your Name" and it neglects to mention English subtitles are available).
And to be more specific about the film, it's a teen sci-fi film with dick and breast groping jokes. It was probably too grown up for the crowd that watches animation with their children, but not mature enough to be viewed as "adult animation". This probably shouldn't work against it, but I suspect it did -- Adult Swim is probably the closest things to a teenage animation scene the US has.
The subtitles I watched made no attempt to explain or introduce some cultural things. The Ore/Watashi scene just translated the dialogue as "I (Ore)" and "I (Watashi)", if you didn't already know, that scene would make no sense. And I only got it because somebody asked how the scene had been dubbed on the thread, when the film got it's UK release. Had I seen it clean, it would have lost me too.
Then there's the whole things about Americans being culturally ignorant, but perhaps even worse than that, they apparently actively dislike depictions of foreign countries that don't match their expectations. There was a story that Disney really upset Iron Man 3's Chinese co-producer DMG Entertainment, by refusing to use a very expensive and difficult crane shot that it had to battled to arrange, except on a TV in the background of another shot. The reasoning? Americans weren't comfortable with a depreciation of modern China, that wasn't rice fields and paddy hats. I wonder if the attempt at a more nuanced depiction of Japan, that doesn't really fit into American stereotypes of Japan, put them off.