I believe that this is the most pertinent point in regards to why journalism looks the way it does. I would not still be in this field if I hadn't had a full ride to college. The job is skewed to those already coming from a place of economic security, and as a result you'll frequently see those people being white males. (Which isn't just a journalism problem, but a far great societal issue.)
I will say it's naive to think many people aren't working hard to get minorities a shot in this industry. I've had four separate occasions now in which an editor told me either explicitly or implicitly (and probably illegally) that the upper levels of management didn't give them the OK to fill that opening with a white male. It sucks. But I've also seen the bullshirt plenty of talented women in this business have to deal with that I will never have to. They're very much on an island, which is why organizations like AWSM are necessary and why it's silly to take umbrage at what Wilder tweeted.
Speaking from personal experience, when I was the editor at a 15,000-circulation daily for two years, I had only four females apply for openings out of 100+ applications. One I hired as a part-timer, another I would have but she wasn't able to commit to nights because of her college schedule, and a third I was hoping to hire to a full-time spot until she flaked out and never showed for her interview or even called to say why. Still haven't heard back. Ha.