You're right. If he wanted justice, he could have gone after folks on the ground in the Phoenix field division. Instead, he had to go directly after the US Attorney General, even though he didn't know the extent of Holder's knowledge of the operation.
The result? A marginal media blitz, followed by the President effectively shutting down the investigation via executive privilege. Issa got to play the inquisitor for the cameras, but in the end, nobody's been prosecuted and nobody is likely to be.
Sometimes it’s nice not to destroy the world for a change.