Speak up and say it.
Ok... In short I think it's the "shock" factor, and media sensationalism for ratings.
It seems to me that the national media only covers stories like this when it is nice kids from affluent families. It's all about latching onto a story that will grab peoples attention for the media, so that they can milk that story for as long as possible. It's more shocking when stuff like this happens to affluent families, and so the media runs with it for months. Same kind of deal with Jon Bennet Ramsey, she wasn't the only little girl to be killed, and also not the only one where her parents where suspects, but she was a beauty pageant contestant from a rich family in a rich neighborhood, so she gets more attention.
I'm sure there have been many other teenagers go missing under suspicious circumstances since Holloway. Has anybody heard about them on the national news?? A few maybe, but not to the same extent. How many kidnappings have there been over the past few years in Arizona?? But they don't get national attention because it's mostly poor (often illegal) immigrant girls that are getting kidnapped for human trade, it's just not as shocking or dramatic as a pretty teenage girl from an affluent family disappearing in Aruba, but still it's just as tragic.