Pretty good article about the very bad effects of ignoring past administration's crimes: Prosecute Trump to the Full Extent of the Law
There is a reason that “Equal Justice Under Law” is carved into the physical architecture of the Supreme Court above its primary west entrance. Far, far too often, America has not been a society where we are all actually subject to law equally. And yet the notion that politicians and billionaires are supposed to be the same under the law as the poor and the oppressed is a powerful principle. This aspiration is necessary for the development of a sense of community and has served as a powerful impetus for America becoming generally less unfair over time.
Nixon's pardons, Reagan's pardons, and Bush (Senior and Junior) pardons all lead directly to Trump: Somebody who actually campaigned on being a criminal, because crime has no consequences for the rich and powerful. If we want to break that deadly cycle we have to stop ignoring crimes.