That's because the impeachment was about more than Clinton. It was, I think, an effort to symbolically overturn the 1960s revolution in manners and morals that, in the mental universe of the political right, Clinton appeared to embody. The Republican pundit William J. Bennett published a book that year titled "The Death of Outrage," suggesting that the public's capacity for empathy in cases like Clinton's had risen to dangerous levels, requiring a reversion to earlier, less sophisticated codes of conduct.
If only we had lacked for outrage during Clinton's presidency! The impeachment debacle, as has become increasingly clear in retrospect, was caused not by a dearth of indignation but a surplus of it -- a spilling over of resentment and moralism. Although public majorities insisted that Clinton deserved no great rebuke, their voices were drowned out by the Inquisition.
Before Clinton, of course, there had been scandals aplenty; it was in the 1980s, after all, that the term "feeding frenzy" was first applied to journalists instead of sharks. But in the 1990s, a mix of factors came together to create our zero-tolerance scandal culture.
The left, displaying what soon came to be called political correctness, ceased forgiving even unintentional slights toward historically oppressed groups. The right -- grappling with the stark reality that many values of the 1960s were probably here to stay -- began seeking scapegoats.