When the McCain-Feingold law was being debated, many decried it. Some on the basis of free speech, but just as many because it’s stated goal of “getting the money out of politics” was naive to the point of stupidity. The river of money, we argued, would always find a path.
And lo, cometh the 527.
527s do not increase transparency, they decrease it by fogging the lines about who is or is not a contributor: you don’t give money to candidate X, you just gave it to an advocacy group which then just happened to campaign against candidate Y. The extra layers create plausible deniability for shady pols.
527s increase the negative tone of campaigns; they cannot say anything good about X, but they can say bad things about Y.
They generally degrade the discourse by immunizing candidates from blowback. A 527 can produce an ad of dubious taste and/or accuracy attacking Y while X stands above the fray. X can even go ahead and distance himself from the anti-Y groups; he can even make a show of distancing himself if he wants. “I really deplore these ads depicting my opponent as a serial rapist of dead oxen. But I’m prohibited from “coordinating” with them, so, golly, what can I do?”
The problem is not 527s per se: they are just the current manifestation, just as “soft money” was the last one. Attempts at limiting the amount of money spent on politics only serves to force the river of money underground and through other channels; it’s a fool’s errand and should be abandoned.