Though I took a long way around (typical!) by trying to set the stage of what is in motion in the Mid-East, there are really only a couple of factors that ultimately must be considered.
The first is that the Palestinian terrorism, when it is not being directed upon themselves, means to disrupt the democratic system and economic success that Israel represents. Israel is a marked contrast to the thuggish, theocratic and nihilistic alternative represented by the Palestinians themselves, and they can't bear the comparison.
The means the Palestinians employ - kidnappings, suicide bombings, rocket attacks on civilian population, the use of their children as involuntary shields and martyrs - are abhorrent and attention getting, but they have not stopped the viability of the social and economic experiment of the Israeli state.
The Israelis could certainly choose total war and steamroll the Palestinian militaries at the the cost of large civilian casualties. They limit themselves to limited incursions and only after extreme provocations. And, thus far, they have self-limited themselves by focusing on strong defensive measures, including systems such as Iron Dome.
No country, no people can tolerate such attacks and the Israelis have taken an extraordinarily moderate path in response. But it is questionable as to how long they can maintain such a path in the face of certain attacks from close proximity.
Second, the Israelis face an existential threat from Iran, the greatest state sponsor of attacks against Israel and one that is actively developing weapons of mass destruction. They are physically a more distant enemy, of course. As a large country with WMD capacity, Iran would have the wherewithal to destroy the economic viability of the Israeli state while being insulated themselves by distance, size and dispersion of cities, population and infrastructure.
The most common discussion is of delivery of Iranian WMD by ballistic missile. Lots of technical problems with that, but devote enough resources to it and Iran will eventually come up with something more effective than what they have right now. For now, it seems Iron Dome will be effective enough to stop any attack of that type for the forseeable future.
A single small nuclear device's EMP, delivered by a suicide aircraft at high altitude over the small state will destroy Israel, even if the blast effects will not. Iron Dome can target that delivery platform as well, though it remains to be seen how they will integrate IFF systems to allow Iron Dome to do so.
If the West does not act in concert, if the Obama Administration has come to accept a nuclear armed Iran, if other Gulf states come to accept a nuclear armed Iran - Israel must act alone or accept its own eventual destruction.
In a couple of months Iron Dome may offer the kind of effective shield for the Israeli homeland that will allow them to pursue a more definitive approach to external threats.