“Why...would America want to learn Navajo?”
Why not? Just about any language can be interesting and helpful to understand something of history, culture, even botany and weather. Not everybody needs or wants Navajo, but we have room in our vast country for expertise in all sorts of random things. Might be useful to know that in Navajo, a certain plant name means “cure for hangover” or a place name means “flood zone”. Just sayin.