Are you sure you have the time-line right? The Sudanese offers to the US occurred in '96, not '98. By that time, as you know, bin Laden had moved to Afghanistan.
In any event, that's not really the point. Did the Clinton Administration fail to break the back of international terrorism? Certainly. Could they have broken its back? Probably not.
To beat al Qaeda, one would have to anticipate its every move. The Clinton Administration, and other Western governments, thwarted many terrorist attempts. (There was the guy who was caught trying to bring explosives into the US at Port Angeles, WA; there was the plot to blow up the Pope in the Phillippines; there were others.) But they, and the Bush Administration that followed, apparently did not anticipate every threat.
The FBI and the CIA are at fault, too. Yes, they answer to the President...to a degree. But Louis Freeh was famously hostile to the Clinton Admin. He fought lie-detector tests on FBI agents, as he was arguing in favor of such tests on CIA agents. Had FBI agents been subjected to lie-detector tests early on, Robert Hanssen might have been caught much earlier. And some of the intelligence that he gave to the Russians apparently made its way to al Qaeda.
The CIA? Why didn't they go to the President, requesting funds for more Pashtun-speaking agents? Because that wasn't the way they were thinking.
The Bush team failed to act on the recommendations of the Hart-Rudman report, issued in January of last year. They shelved it, and vowed to begin their own (redundant) study a few months later.
When the Hart-Rudman report came out, the press greeted it with a big yawn...and then got back to the business of ferreting out every last tidbit of the Marc Rich pardons, or the rumored White House vandalism, or Chandra Levy. They failed to give it due consideration.
The whole of Western society failed to grasp the threat of international terrorism and take it seriously. That all changed, forever, on Sept. 11. But it's an irrational reading of recent history to pin it all (or most of it!) on one man.
(Apologies for the length of this rant.)