The State of Israel gained full independence following a terrorist attack which killed the ranking English administrators.
September 11 was an overwhelming success on the symbolic level, and terror is all about perception,the casualties themselves are insignificant, at least until the dreaded nuclear terrorist event actually happens. One attack could hardly have hoped to achieve more.
So, terror is effective, but rarely so. It needs to be spectacular, out of the ordinary, and it needs to succeed in nudging events just so in the desired direction. Another suicide attack against an Israeli city has been done so many times before it people are numb to it. A retaliatory incursion like this one with a massive civilian death toll does a lot more to move public perception, or in this case world opinion, since that conflict is as seminal as ever.