There is valor added by journalists in even niche sectors. A journalist that reports on cars knows about the industry itself and can give an informed take on different developments, he might know how a car works, he might know about different trends in design, or markets, or whatever else. That is his added value.
When it comes to videogame journalism, though, they act as little more than spokespeople for corporations. They generally don't understand the product or how it works (mechanically or in terms of design), and in some cases aren't even adept at playing videogames themselves. The only thing the world would lose if no game journalist ever mentioned WoW again and the devs communicated directly with the playerbase would be the appearance of impartiality journalists give.