I think Isreal worries too much about the worlds reactions. The should just wipe out as many terrorists as they can find. Believe me if it happened on a thursday afternoon, no one would care by saturday nor remember by the following tuesday.
They react by isolating Israel economically, diplomatically, academically...
Israel has to worry about the world's response since she is not an island or self-sufficient.
As for no one not caring... if only that were true. But the world does care. And is not afraid to "punish" Israel. Israel has felt this before.