I am against government financed campaigns because the government, i.e. those in power, get to pick the players. The Reform Party barely got any public campaign funds; I don't think (?) that the Libertarian Party ever does. 
Depending on the size of the company & size of the contribution, the corporate board will have a lot to say about corporate contributions. 
Government regulation & taxes can make or break an industry; destroying jobs & lives. 
One could argue that special interest groups are merely bundlers, speaking for those who voluntarily contributed. Let the individual voters contribute directly. 

I agree that we need some form of balanced budget amendment to curb government spending.