This phenomenon is not peculiar to the Obama Administration.
This really ramped up during the Clinton Administration.
The Bush Administration did nothing to stop it. In fact, there was more greenmail paid to left wing groups in the Bush Administration than during the Clinton regime.
Much of the greenmail was paid by the financial industry following the repeal of certain provisions of the Glass-Stegall Act that legalized mergers subject to regulatory approval. Left-wing groups would relent on their objections to mergers in return for payoffs from the Justice Department slush fund raised from CRA settlements.
What you are describing sounds more like a shake-down scheme than the pursuit of justice.
Yea Bush and Clinton were corrupt too. This is a part of draining the swamp. My how the powerful have taken advantage of the people.