Why not? A large portion of the punishment is just going through the court system. For a significant amount of time all you can do is stress about your next court date, you can't get work and burn through your savings. In his case he has already paid tens of millions in his money and the company paid billions. He spent four months in jail, and has spent years out of work.

By the time a pardon comes the persons life is usually already in deep distress, and whatever they were working on is likely already over. I don't see why it's such a tragedy to let some people get pardoned who maybe don't deserve it.