Yeah, I don't understand the comments praising Korea for this. A tradition of prosecuting political opponents and then pardoning all of them is a mockery of the rule of law, regardless of what they actually did.
Not that I agree with the pardons, but former presidents are usually old. Letting your political opponent die in prison can have a massive backlash so most presidents would rather not let that happen.
If he's pardoned and released, sure, it's a mockery, but holding public officials accountable for their abuse of the public trust is necessary to the rule of law and democracy.