Concerning a family so egregiously malfeasant as the Trumps, there will no doubt be many state and local cases against them. But the desire among many is to restore some dignity to the office of President by holding the President and his advisors/family accountable for the many acts of depravity they engaged in while in office. The desire is to remind future holders of the office that the President is not above the law.
While the policy of the U.S. Dept. of Justice is that no sitting President may be charged with a crime, it is not that no sitting President can commit a crime. And the moment he ceases to be President, he is chargeable for any crime he committed for which the statute of limitations has not run, regardless of what office he held when he committed it. In terms of restoring the dignity of the office and its penumbra, almost all of that is governed by federal law, over which the President has fairly unfettered pardon power.