There's a difference between bias in news reporting and opinionated talk radio/talk TV. You can say that CNN, ABC, CBS, etc. show bias in their news reporting (as shown in Bernard Goldberg's book BIAS). When Fox News has Bill O'Reilly, Hannity and Colmes, etc., on, they are offering opinion and commentary.
Fox News and conservative talk radio were a response to the liberal media bias (hello Dan Rather) in this country. There was a need for it. Both entities are doing well in the ratings...Now Air America wants liberals to have their own voice on talk radio. If it's done well, they could also succeed. Realize that a)many liberal attempts at talk radio have failed before but maybe they can find "their Rush"), and b) "Rush wasn't built in a day". It took awhile for Limbaugh to get his audience.
The book South Park Conservatives pointed out that Limbaugh came along right after the Fairness Doctrine was repealed. Now, a talk radio station didn't have to offer both sides--they could put on a Rush and not have to also put on a Franken. Talk radio is a business and if a station feels Rush draws ratings and Franken doesn't, the government shouldn't force them to carry Franken as well.
Should the government force a country station to play hard rock as well? No...
Of course listeners are invited to call in and debate the host. Talk radio isn't news, it's commentary about news. Conservative-based stations have made their mark. Now it's up to liberals to do the same. The (un)Fairness Doctrine helped spur conservatalk, true. But many liberals want to bring it back because they feel it'll give them equal time.
But stations, given that situation, would rather not put controversial issues on the air.
It would cause a drop in ratings if they had to air some liberal hosts (by force).
So opinions of all types are welcome on radio but since it is a business, it's up to talk hosts and their producers to give us shows to entertain and enlighten. If they fail to deliver, so be it.