This post will lay out the socio-economic argument for assassination.
My first post dealt with the legal and moral issues of assassination. I argued that the terrorist leaders do not have the right of due process because they are not civilians. Even when they might have such a right, such as when Israel uses assassinations to retaliate, that right is overridden by the society's right to defend itself.
Assassination, whether forward looking (preventing attacks) or backward-looking (punishing for past attacks) surely has valuable benefits for Israeli society. Both uses create a disincentive for Palestinians to become terrorists because the risk of death increases when Israel is capable of killing them at any time. While this disincentive might not affect a potential suicide bomber, it certainly would make leader in the chain of command think twice before sending a bomber to a bus in Tel Aviv. Assassination should therefore decrease the overall instances of terrorist activity, since leaders will be more wary of launching attacks.
Moreover, as noted earlier, the threat of death disrupts the smooth communication between leaders and soldiers. A leader in fear of his life will have to take measures to protect himself, and every measure diminishes his ability to promote his objective of attacking Israel. If planning and training becomes more difficult, attacks become more sparse. And the less often bombers can be sent, the chances of them being caught increase. So the overall number of successful attacks should drop.
Another element of assassination is that it makes Israel's citizens feel like justice was served. Steven R. David argues that assassinations are justified because they take revenge on the killers of Israelis. He argues that revenge can be a good thing if done within a context. I'm not sure I agree that morally it is a good thing, but the feeling of vindication Israelis feel when their killers meet their fate is certainly a benefit for a society like Israel. While Israel is the most western nation in that region, it still exists in a region of tit-for-tit. The classic Arab societal response of vengeance killings (common among Palestinian subgroups) does have its manifestations in a society like Israel that is so imbedded in the Middle East. It's not a stretch to argue that many Israelis would support killing for vengeance.
His other point is better taken. Another primary function of punishment is retribution. A crime must have a punishment. While this is a moral argument for punishment, most societies would agree with retribution as a reason for punishment. The society feels more at peace if criminals receive their just due. That feeling is a benefit. This argument is similar to the one above, except that, in my mind, retribution is a more proper reason to assassinate than revenge.
Of course, both retribution and revenge can be had after due process, but given the current climate, the costs of invading and capturing terrorists greatly exceed the costs of killing them, while the benefits would be more or less equal.
On a side note the benefit for society is increased in more than "feelings of vindication." The visceral effect of seeing the charred remains of a terrorist's car is substantially greater than hearing that some hit-squad captured him or seeing him put in prison for life.
Lastly, Israel's policy of assassination will make it more acceptable around the world. The greatest weapon of the terrorist is his ability to hide among civilians and be protected from large scale assaults that are needed to arrest him. Israel's policy has negated that weapon by allowing other countries (like the US) to kill the terrorist directly. Criticism of Israel's policy diminished as it became more common. How many times is the EU going to condemn assassinations? The more it's done, the more acceptable it becomes.