The thing about the Cowboys is it kind of feels like a self-fulfilling prophecy in terms of media coverage. If the media over-covers the Cowboys consistently for decades, of course they seem more newsworthy to the average fan.
A lot of people hate the Cowboys, I presume because they were extremely good during the development years for two separate generations of fans. That makes the Cowboy's so newsworthy, presumably, because people will want to hear about them if they win, and even more people want to hear about them if they lose.
But I don't remember the Cowboys ever being particularly good--and I have gray hair. They haven't been truly relevant in my entire memory, yet they are still treated as such because of this self-fulfilling prophecy that the Cowboys must be covered at all times. The apparent fascination with Jerry Jones, who never says or does anything remotely interesting, is another odd one.
And obviously it stems from the data, as 8slim says, that backs up the interest in the Cowboys, but that is just an example of media being boiled down to exclusively covering the handful of most popular things, 100% of the time.