When you look at it from the perspective of the officers, this plan was a win-win proposition. Even if it gets thrown out it court, they stopped the allegedly illegal operation. When there is no consequence to the officers themselves for their actions, then the ends will justify the means.
(It's unjust, unethical, and possibly illegal, but it's the same reason people are still reading and discussing Machiavelli 500 years later.)
The odds of heads rolling, going by previous non-attempts at holding these agencies responsible for their actions, seem to be low enough that they're quite happy to engage this behaviour without fear.
And as for bringing about a change that would see future incidents causing them to be held accountable? I think the average person, and therefore the population, feels entirely powerless in that regard. I mean the US voted for a supposedly liberal, progressive President who even has it on his campaign website [1] that he would "Protect Whistleblowers", who has then gone on to prosecute more whistleblowers than all other President's combined [2].
So it's no wonder why people feel powerless, and it's no wonder why any change to these situations is certainly not coming in the visible future.
That's why it's such a shame the Obama administration especially (but probably the previous admins, too) fight to hard to protect the criminals in the government, instead of punishing them. That just sends a message that they can keep doing this sort of stuff, and nothing will happen to them.
I'm not going to look for it now, but I remember a speech from Obama in relation to torture and he was basically saying that "he has the CIA's back," if the media or whoever tries to get those people responsible punished for it. It was from a few years ago, in this first term.
How is that a win? You've frustrated criminals for all of about 5 minutes. Further, you've alerted them to potential problem areas to avoid in the future.
Congratulations, you've just made a smarter criminal. It also doesn't help that the FBI is a public institution and is required to respond to FOIA requests.
The FBI does way more damage when it swings and misses than simply not doing anything at all.
(It's unjust, unethical, and possibly illegal, but it's the same reason people are still reading and discussing Machiavelli 500 years later.)