For a democracy to function effectively, those in power have to be accountable to those who vote them in. This can only be achieved if there is an independent source reporting on the actions of those in power in a critical and balanced manner. An effective means of achieving this is through a public broadcaster, providing information which is as close to the facts as humanly possible.
Unfortunately, broadcasters of information for the public good are not all that common around the world. The Economist Intelligence Unit (EIU) publishes annual reports on 167 countries concerning how closely they approximate a democracy. If you click on Democracy Index you will see that the EIU divides countries up into Full Democracies, Flawed Democracies, Hybrid Regimes and Authoritarian Regimes. Australia is one of only 21 countries currently rated as a Full Democracy. One of the key features of a Full Democracy is independent media, without which civil liberties and political freedom cannot be inherently assured. This is why an independent public broadcasters like the ABC, with a specific charter to ensure that it operates for the public good (refer to Section 6 of the ABC Act 1983), is so important for our democracy.
For a discussion of countries that aren't so fortunate, please refer to Radio National's The Roundtable (Growing threats to press freedom around the world). Or closer to home, recent developments in the Solomon Islands where the government has ordered the SIBC (Solomon Islands Broadcasting Corporation) to not broadcast any reports that are critical of that government. Effectively turning their version of the ABC into a public relations service for the current government. Could you imagine the Australian Government requiring that the ABC only report stories that support our government?
Support for independent public broadcasters is far more than the entertainment content they provide.