Back in the old days, the news did not influence tourism that much I guess. All you had was talking to someone you knew to get the latest information on traveling, no internet for bad news. Bad news are the news that bring the money, focused to make money for their own benefit. I doubt there is some kind of lobbying from the tourism industries that are trying to keep the dollars in USA, scaring people every way they can. They probably succeed as many of us are scared by the flash news.
The murder rates are declining in USA, but still is one of the highest rate in the developed countries, after Mexico but probably not that far, still we travel with confidence. http://www.rawstory.com/rs/2013/09/u-s-murder-rate-higher-than-nearly-all-other-developed-countries-fbi-data/.
Back in the 1990's, it was pretty scary, the murder rate was much much more than today in USA, but people still traveled a lot in those days.
I try to read the news from someone who's been there, and restrain from reading the interest based bad news from the media. This should help me decide to go further in Mexico.