The pardon power seems to be very broad, and is most likely constrained by politics more than by statute. Set aside the idle speculation about a president pardoning themselves, pardons have been granted to whole classes of people for crimes you have yet to be charged with. Consider Jimmy Carter pardoning draft dodgers or Abraham Lincoln pardoning soldiers who fought for the Confederate army.

Absolutely. But if we're going to give our president a power that could be used too liberally, it's good that it's the power to let people go free instead of the power to imprison (or worse) anyone for anything he wishes.