Why does the government want us to worry about who is doing the speaking?

There's an American tradition of speaking pseudonymously, most prominently exemplified by The Federalist Papers. Why not listen to what is being said and apply your judgment? Have we lost the ability to judge without seeing who's saying it? If our critical thinking is that poor, what's the point of letting us vote?

And listen to how desperate Obama sounds here:

They're fighting back. The empire is striking back. To win this election, they are plowing tens of millions of dollars into front groups. They are running misleading negative ads all across the country.

Why not just argue on the substantive merits of the issues? He's inviting us to think in stark good versus evil style — straight out of fantasy movies. You need to know who is saying something, not what is being said, because you should side with the good guys — his government — not think in any detail about the issues.

I hope you notice that Obama is not talking about the identity of campaign donors. He's talking about independent speakers who don't want to reveal the names of all their donors.