Of course a rock band could be huge, but it is not just the media that determines current taste. there are many factors.
music has taken a step back in terms of distribution. we are back to selling "the single" instead of full albums. not saying whether that is good or bad (i love albums though) but that's what sells now.
you don't need to leave your home to hear music. just dial up youtube or what have you and go to town. live shows seem are not in fashion. of course there are live shows, but they are not the main method of distribution like it was back in the time of the troubadours. Rock embraced the album and live show. And i think it could be argued that a live rock show where you (supposedly) see musicians playing instruments is a little more interesting than lipsynched pop show or pressing play on your macbook and rapping on top, on average (there are some amazing hip-hop live shows). and so, for a kid growing up with, for example, mostly hip hop, the desire to see a live show is not as strong.
like most things, i expect a big swing in the opposite direction at some point. kids who have only seen their favourite music on youtube from the comfort of their ipad are going to figure out what they are missing, be it rock, albums, live shows. well, i hope that's what happens because i've been playing in bands all my life and have seen the decline of live music and album listening first hand. either that, or my band just sucks.