Although it is often said that Palestinian suicide bombings killed the Israeli left, I don’t believe it’s that simple. Both happened at the same time, but that does not prove cause and effect. The decline of the Israeli left set in long before the suicide bombings started, and went on after they stopped.
I think the real reason for the decline of the Zionist left is that it has lost credibility. Young Jews who chose become either non-Zionist/anti-Zionist or right wing Zionist. Perhaps the suicide bombings contributed to the loss of credibility (they proved that Zionism was not so benign to the Palestinians), but there are other factors too, like the “New historians” who destroyed Zionist myths, or the ongoing colonisation of the West Bank, which is supported by the Israeli left, but also goes against its universalist values. That’s the problem with the Zionist left, it tries to combine contradictory values, particularism and universalism.