"Why would they seek retribution for willingly dropping all of the evidence in a shredder, letting the bad guys know how to plug the leak, and walking away?"
There's no evidence of that happening! And as many have said, IF the proper channels failed, THEN you could go public. For many of these ongoing issues, the evidence can't be shred, and in many cases doing so is in fact a viable resolution to the problem.
Do we have a single example of one of these high profile folks someone saying "I reported egregious behavior properly via the whistleblower protections, but now all the evidence is gone, but they're still doing bad things so I decided to go public"? I mean, someone had just said "hey, we shouldn't be doing this, should we?" and then everyone said "you know, you're right", and then stopped, that actually sounds like a working system. And we don't know how effective the current system is -- many (obviously not all) abuses may have been stopped via whistleblower protections done properly, but some of this will be classified so that information getting out is both unnecessary and unlikely. And as I said before, we DO know that a few thousand of these a year go on largely without incident.
But even if we grant that going public was the only way, again I think the difference between approaches are vital. Taking precautionary steps to ensure very little classified information gets out, and that the information that does leak is vital to proving the abuse case is far less destructive than taking loads of evidence and giving it to wikileaks or foreign press. Many of the documents so leaked have hurt diplomatic and intelligence concerns in areas that are disconnected from the targeted abuse. That is unnecessary and what I find punishable, and where I think Drake could be treated with leniency due to his diligence in keeping classified information safe.
Lastly, just to be clear, I'm not supporting the actions of the organizations either... I was in DC protesting the Patriot Act with many others years ago because I think the problem is more in the laws that allowed this sort of thing to happen. The problem is that the actions may have been LEGAL, if unethical and not what the voting populace wanted or intended because we let these privacy eroding laws happen in the first place. We need more voters to put pressure on politicians to write laws that clearly disallow this sort of privacy-invasion in the first place; that would make whistleblowing more effective (and hopefully less necessary) because the abuses would be more clearly illegal.
Sorry that's so long, I'll stop ranting now.