FOX has long been on the MMA bandwagon. The Best Damn Sports Show, Period was the first cable show to regularly feature MMA stars once the UFC got back on cable pay-per-view. FSN airs PRIDE and IFL; UFC is on FOX Sports on Espanol.
I couldn't tell you why our online and television competitors don't cover MMA, especially when the big one makes time for boxing, kickboxing, and K-1 (not to mention spelling bees, tiddlywinks, and hour after hour after endless excruciating hour of sportswriters screaming cliches at each other).
As for newspapers, many newspaper editors are creatures of habit and can be slow to adapt to changing times, which may in part explain why it sometimes seems like no one reads newspapers anymore. How many papers still have greyhound or horse racing listings? How many people actually follow either of those sports anymore? One legitimate point about newspaper coverage regards the 10 p.m. Eastern start time to most pay per views. If a newspaper needs to roll off the press at midnight and the main event doesn't get started until 12:15, it won't make the next day's paper.
Still, things are slowly changing. It seems with each UFC PPV, there is another major newspaper on board. Most papers of note in the Southwest, including the Los Angeles Times, are starting to give the sport regular coverage. And, you might have noticed that the ignorant, trashy "this is human cockfighting"-type stories seem to be finally vanishing from the media landscape. So things have improved, even if it is incremental.