Those on the left who worry about media concentration generally prefer competition without profit maximization to competitive profit maximization. In a socialist society, where presumably profit maximization won't be a goal, media concentration -- concentration of the media in the hands of the state -- will be a problem. What about capitalist society? I, too, prefer the New York Times, the Wall Street Journal, and the Financial Times to local commercial media and even much of the local non-profit media, but it would be better if the United States were like Italy, where a number of left-wing mass-circulation newspapers compete and even field foreign correspondents of their own. The Financial Times is useful, but the British media wouldn't improve if the Financial Times monopolized readership, without competing with The Guardian, etc.
Also, the thing about democracy is that people need to acquire skills and experiences that would enable them to participate in politics, and skills and experiences necessary to do so in the production and distribution of ideas are essential to democracy in modern society. That means that there ought to be spaces where people can acquire such skills and practice them, even though the results of such practice aren't exactly stellar in the eyes of passive consumers.
Of course, if you were solely looking at media workers' welfare, without thinking of readers' interests at all, every country having one giant media with no competition whatsoever would probably be better, as it will never go bankrupt and can get higher rents that can make for higher wages. But the production and distribution of ideas isn't exactly like the production and distribution of steel or airlines, in terms of its implications for democracy, though even in the latter kind of production and distribution, the interests of the rest have to be balanced against the interests of workers of particular enterprises in a socialist society (which is the point of co-management).
-- Yoshie <http://montages.blogspot.com/> <http://mrzine.org> <http://monthlyreview.org/>