Aside from the moral and legal problems associated with such attacks - whether by rockets or suicide bombs - Hamas and other militant groups failed to understand that terrorism rarely succeeds unless the insurgency deploying it is already strong enough demographically, militarily and politically to defeat the occupier.
With the outbreak of the al-Aqsa intifada, Hamas's reliance on extreme violence - in its rhetoric as well as actions - overshadowed other forms of Palestinian resistance, giving Israel the necessary cover to deploy an even greater intensity of violence across the Territories.
Successful non-violent movements, such as in the US, India or (for the most part) South Africa, succeeded because, in Gandhi's words, they sought "to convert, not to coerce, the wrong-doer".
As Gandhi explained it, the goal of non-violence must be to obtain the cooperation of one's opponent to achieve a just end to a conflict, utilising means that reflect rather than degrade the justice of one's cause.
Rhetoric matters too.
Israel has justified the war on the grounds of its security concerns.
When during the past year Hamas leaders talked proudly of making "death an industry of the Palestinian people" and creating "human shields" composed of old people and children, or declared Jewish children everywhere to have become legitimate targets of murder (as did Hamas commander Mahmoud Zahar in a televised broadcast on January 5), the movement helped normalise the intensifying siege on Gaza, playing into deep-seated Western - and particularly American and Israeli - stereotypes of Muslim irrationality and brutality.
As no less a supporter of Palestinian rights than Norman Finkelstein argues, it has left "Palestinians ... [with] little to show for the violent resistance ... It is at least arguable that the balance-sheet would have been better had Palestinians en masse adopted non-violent civil resistance"
In plain English: how's that terrorism workin'?
H/T: Jay Currie