Or they simply assert a need to clear the air of a general cloud of suspicion they have helped to create. The 1996 Clinton-Gore media campaign was probably the most brazen abuse yet of soft money. But that doesn't make it illegal. Campaign finance laws should be obeyed to the letter, but, in a competitive democracy, there is not even an abstract moral obligation to obey them in spirit. All reforms of this sort tend to erode over time as people figure out ways to evade them.
Tax reform is another example.
That doesn't mean the reforms are bad or pointless. It just means that they need to be traded in for a new model after a certain number of years, just as your car does. The Republican Congress, of course, has prevented precisely that, even as Republicans complain about Democratic campaign-reform abuses. They are right to point out that, logically, when someone breaks the law, this demonstrates flaws in that person, not in the law. But, when many people are behaving in ways that violate a law's spirit, though maybe not its letter, that probably demonstrates flaws in the law rather than in all those people.