I'm sure the people of Afghanistan didn't want to be invaded. Bin Laden wasn't one of them and is quite a different story. Bin Laden wanted the US to invade because he believed that the Mujahadeen(which he was a part of and partially funded in the '80's) had not only defeated the Soviets and forced their retreat from Afghanistan but almost single-handedly brought the Soviet Union to it's downfall. He believed that he could do the same with the US. Please note that it took nearly a decade to defeat the Soviets. Bin Laden was willing to be patient in order to bring down the US. He still is. He didn't expect to win right away. He expected to gain control of the country back after the US left, either by defeat or simply lack of will to keep fighting. It's only been six and a half years and the Taliban is already resurgent in many areas of Afghanistan. The Taliban could come out on top if the US doesn't have the will or means to stay and beat them back down. The winner of the war for Afghanistan has not been declared yet. That alone is a victory for Bin Laden, that they haven't been completely crushed into oblivion by the US yet. They are willing to take heavy losses in the pursuit of victory, as long as they recruit enough to replace the dead and they are willing to wait decades if necessary. We are far more impatient, that's a weakness in this situation.
As for the Muslims being forbidden from killing women and children, Bin Laden considers himself an Imam and thus capable of interpreting religious texts himself. In an interview with Al Jazeera in 2000, Bin Laden made it clear that, to him, civilians of all stripes, including women and children, were fair game since his organization was acting out of vengeance for acts supposedly perpetrated against Islam. In Jihad, revenge killing of women and children is permitted.