Dallas and Houston are almost as big (with worse crime rates) and barely make the news. They are also in a Republican state, so Fox News, talk radio, and the like don’t focus on their issues. It’s political. They don’t actually care about crime in these places.
See also: All the talk about Detroit, a very small city.
You're looking at the here and now, but to understand the prominence of cities in the American zeitgeist, you need to understand the history of those cities too.
A hundred years ago Dallas was a small city of less than 200k people, not particularly relevant to anybody outside Texas, but Chicago had a population of 2.7 million and was the economic powerhouse of the entire midwest. And Detroit seems like a generally irrelevant city by the numbers today, but 100 years ago Detroit was America's 4th largest city and in the subsequent decades rapidly became an industrial powerhouse with the rise of the automotive/war industry. Detroit seemed like the future of America, it became very prominent in the American zeitgeist at this time. When people express dismay with Detroit, they're not merely responding to the present conditions of Detroit but also Detroit's failure to make good on the expectations people used to have for the future of Detroit.
If it makes you feel any better, I think 100 years from now people will probably talk about Dallas like they talk about Detroit today.
See also: All the talk about Detroit, a very small city.