Would you be comfortable with the only investigative journalism being carried out by the government?
Sure, the BBC (British) or ABC (Australia) model seems to work well - but there's been funding spats in the past.
It's not that hard to imagine a world where the Prime Minister thinks "These silly ivory-tower journalists are just using their rag to rail on me! Why the heck am I signing off on more funding. Cutbacks!".
That and there's many countries where I'd rather an independent journalistic service.