And, Ford didn't want the government to be to dragged down with it's pursuit of Nixon, who by then had his reputation ruined.
So, he decided he and the Congress couldn't focus on the needs of the government and the prosecution of Nixon at the same time. I think the difference between Nixon and Clinton, though, are that Nixon's reputation had been ruined, and that was plenty enough punishment, in Ford's eyes. Clinton, on the other hand, has no shame, and the press was supporting him, thus he never felt the kind of punishment that fell on Nixon.
But you're right, that it set a bad long term precedent. All the more reason we need to elect leaders who have solid morals.
ML/NJ