For one thing, many assumed that, while Saddam would continue playing his UN bluff game, he would not in the end risk military confrontation. Many also doubted the coalition would take military action without wide international support - support which is currently limited to about 40 countries.
And those unable to explain why Saddam has chosen almost certain death forget that Arab culture stresses maintaining honour and reacts to challenge in cowboy style.
More importantly, they have also overlooked the fact that disarmament almost necessarily required the removal of Saddam and his cronies; and, second, that the US military strategies employed to that end could differ markedly from those commonly predicted.
Thus, experts (and others) assumed the US would use its massive air and missile power to achieve quick victory without undue concern for the consequent military and civilian casualties.
One Canberra commentator even predicted the US approach could lead to 100,000 civilian casualties. A new term shock and awe - emerged to describe this strategy, the notion being that the application of enormous power would shock Iraqi leaders into surrendering.
What is now emerging appears significantly different to predictions.
True, plenty of bombs and missiles have hit Iraqi targets but, as with the NATO bombing in Serbia, the enormous improvements in technology since the Gulf War have allowed much greater precision in hitting and destroying targets of strategic importance.
This ability to pinpoint strategic targets (mainly government and military centres) now seems a key element of the US bombing and missile strategy.
Importantly, it suggests that damage to housing and civilian casualties may be relatively small.
The US seems to be pursuing other strategies to minimize the loss of life of both innocent Iraqi civilians and reluctant members of the armed forces.
The importance of the friendly Arabic broadcasts and leaflets from US planes and other psychological warfare may have been under-estimated.
Considerable numbers of armed forces are surrendering voluntarily and the hierarchical structure of Iraqi leadership must be under great pressure.
Anti-war protesters have based their case importantly on the argument that high casualties of innocent civilians will result from coalition military action.
They have, conveniently, ignored the high casualties Saddam inflicted on fellow Iraqis and that would continue if he remained.
If the US now succeeds in minimizing both civilian and military casualties, these protesters will find themselves on shaky ground.
Such a strategy would also help lay the groundwork for building a better Iraq post war, with the US as a genuine Iraqi friend. The emphasis thus seems less on a speedy victory and more on one that is effective: a quick win is not necessarily the best outcome.
At home, the Opposition Leader Simon Creans claim that Australias involvement has dramatically increased the risk of terrorist attack reveals a failure to understand that terrorists are after us for what we are, not for what we do.
Also, the relative success of the US in combating activities of al-Qaida leaders, and the police response to the group involved in the Bali bombings, has reduced terrorists capacity to operate.
Of course, there may be attempts by such groups (and rogue states such as North Korea) to exploit the coalition involvement in Iraq.
But it is absurd to suggest a terrorist threat that emerged well before the war should stop our involvement in action to bring an international criminal to heel.