"The oft-cited explanations—campaign contributions and the allure of private-sector jobs to low-paid government lawyers—have certainly played a role."
Emphasis on "have certainly played a role." The moment I hear that, I ask why the hell we aren't focusing the conversation there and keeping it there. Guarantee a lot of the "lack of balls" has to do with worrying about future security in the form of campaign contributions and private-sector jobs.
How about we solve for that problem first and see if they still lack balls when they are no longer worried about their financial future being directly tied to those they are supposed to police.