Because it stars a brown Mexican kid called Miguel? I sure hope you're wrong because otherwise that'd be extremely depressing. Why can worldwide audiences watch an animated film about vikings but not Mexican día de muertos? This is a spectacular, if a bit predictable, movie that will wreck you to your core.
It's not so much about the color of his skin, but one reason Mexicans enjoyed the hell out of the movie is that it shows Mexican culture and traditions in a positive way that's rarely shown in such high quality animation. And the music is incredible in Spanish and for Mexicans. But the story itself is kind of predictable, and if you're not Mexican or Hispanic, it
might not have a huge appeal to worldwide audiences.
Emphasis on the word
might because some American reviewers have said they too were moved by the final act, like all of Mexico has been meming about since the movie premiered over here. That might sell it to most audiences outside of Mexico.
Of course, there have been foreign culture-centric movies that have been big hits in the U.S., from Kung Fu Panda to the Lion King and others, but I don't think Coco's story or writing is on par with those. It's ok, but what really makes it worthwhile is its music, visuals, ending and uniqueness in style, as well as being a (mostly) faithful representation of Mexico, or at least, the idyllic Mexico.
