If he had, of course, the now-venerated Al Gore would have had the chance to run against George W. Bush in 2000 without the taint of the Clinton scandals -- a taint that's clung to some extent to every Democrat who defended him and his behavior -- and might in fact even be finishing up his second term right now.
Barack Obama might well have clinched the nomination by now -- Hillary Clinton would have found it infinitely more difficult, perhaps even impossible, to run for the U.S. Senate (much less president) had her husband resigned in disgrace.
At the time, it seems clear that Democrats considered the defense of Bill Clinton to be tantamount to making a last stand against the forces of evil, take-no-prisoners, radical Gingrichism. Had they only seen Bill Clinton then the way they see Bill Clinton now, how different everything might have been for them (and for the rest of us).
John Greenleaf Whittier definitely knew what he was talking about.