FM radio is radically limited in range. You can listen to AM or shortwave across a whole continent, or even across oceans. With FM you're very lucky to hear something over a hundred miles away. AM radio is most popular for news and talk shows, and emergency broadcasts.
When I was living in "upstate" NY (the Poughkeepsie area, which isn't upstate, but that's what it's called), I would regularly listen to AM stations out of NYC (close to 100 miles away from the broadcaster); using just the standard receiver in my car.
FM definitely wins for audio quality. But if you are facing a major national disaster where Internet may be down in various places, you need to have AM. The quality is plenty good enough in most cases. Even in the worst cases, it rarely performs worse than a traditional phone call. Really, the quality issues become apparent mostly because you can easily get partial reception on stations that are extremely far away, leading you to think that the technology is inherently bad. It's not a binary success outcome like digital TV signals. When AM radio was more popular I would often listen to AM stations, with some of them being pretty far away. Back in the days before the Internet, radio was THE way to get informed.
