This kind of power sets a bad precedent that could become norm for all future Presidents that engage in criminal activity. It gives the King/President full authority to run a criminal enterprise with no worries for all involved because President has promised a preemptive pardon.

This needs to be challenged at Supreme Court. Pardons, no matter the party affiliation should not be allowed by presidents or governors.
The president is the head of state, leader of the federal government, and Commander in Chief of the United States armed forces. Not the judicial branch.