Initially the situation was depressing and troubling. It actually goes back to the original Gulf War when Bush senior did not keep to the WMD doctrine. That doctrine, as he himself stated, was 'if anyone uses WMD on us, we will respond in kind'. After Saddam attacked our troops advancing toward Baghdad with chemical and biological weapons, (reference the aftermath known as Gulf War Syndrome), the WMD doctrine called for the nuking of Baghdad. This really should have been automatic. The problem was that Bush senior and his coalition had all kinds of strings and political conditions in place. The main goal was to keep the coalition together at any price. In hindsight, it was a stupid goal because there was no way that coalition was ever going to stay together for any extended length of time. We also should not have put chains on Israel. They should have been allowed to respond (according to the WMD doctrine) to the firing of ballistic missiles at them. What we are now left with is a world were possessing nuclear weapons does not give a nation any security. The non-nuclear nations feel free to attack us openly (Iraqi scuds at Israel) and covertly (9/11 and anthrax attacks on the US). To put it bluntly, the fear factor has been removed and that now makes the world a very dangerous place.
Our current President however, after personally surveying the results of our predicament in the World Trade Center carnage, is fixing to put the fear factor back in play. I dont think he will completely restore the WMD doctrine, which still calls for the nuking of Baghdad, but he will restore it with the most powerful conventional attack the world has ever seen.
Got away with? That's an interesting perspective. We take 3,000 casualties, they lose a country, soon to be two countries, get their financial umbilical cords cut, face a global manhunt, and have no real prospect of getting back on their feet. At prices like these, no one can afford terrorism in the long run. Do the math.
Sure, we could have nuked Afghanistan. That would have created far more problems than it solved, and wasnt' necessary in the first place. An eye for an eye and a nuke for a nuke, sure, but nuking everyone who pulls off a suicide hijacking or bus bombing is foolish overkill.