Hack, I believe, has identified half of the problem. Kids are sponges. They are unlikely to listen actively for long, but they hear everything, and it has an enormous effect. Music is like language, children have to hear it at home to become sensitive to it. The better the music they hear, the more likely they are to develop an "ear" for it. If parents don't expose their children to good music, it is much less likely that the children will develop much passion for good music later in life. Most of my contemporaries listen passively to pretty schlocky music. It stands to reason that their children are not drawn to music, or are drawn only to the most formulaic stuff they hear on the radio, or via downloads.
The other half of the problem is that music education has been removed from most schools. When I was a kid in Philly, there would be periodic presentations by Jazz bands, chamber ensembles, small orchestras, and vocal groups. Nothing like that exists in the overwhelming majority of public schools, even in the affluent areas. This has a huge impact. There is very little in life that is more impressive than being near a big band, or large orchestra going full tilt. The pressure wave alone will knock you on your ass. I was overwhelmed by this when I first heard it, and remember it like it was yesterday. I'm certain that this was part of what ignited the passion for music that I have to this day.
The other half of the problem is that music education has been removed from most schools. When I was a kid in Philly, there would be periodic presentations by Jazz bands, chamber ensembles, small orchestras, and vocal groups. Nothing like that exists in the overwhelming majority of public schools, even in the affluent areas. This has a huge impact. There is very little in life that is more impressive than being near a big band, or large orchestra going full tilt. The pressure wave alone will knock you on your ass. I was overwhelmed by this when I first heard it, and remember it like it was yesterday. I'm certain that this was part of what ignited the passion for music that I have to this day.