Look, Texas, to answer your question: the creation of the Jewish state in 1948 annoyed the left since it deprived it of its designated "victim group" -- the Jews. Since the average left-winger progressive must have a victim group to "support" (by talking), the search for a new victim group started, and, as a revenge on the Jews for daring to attept to not be victims, the Palestinians were chosen. If tomorrow the Palestinians destroy Israel, well, they'll too lose the coveted victim status and some new group -- Muslims in general? Tall people? Urdu speakers? Who knows... -- will be the new-and-improved designated "victim group".
But one thing's for sure: once they can no longer be portrayed as "victims of racism", the Palestinians will hold no further interest to the left and will be ignored. Note how, for instance, the left cares not at all about any outrages done to Palestinians by other Palestinians or by other Arabs. That doesn't fit the "victim of Imperialism" script, you see, so the leftist gets no feeling-outraged brownie points for concerning himself with that.