Israel needs these relatively innoculous attacks to justify its incursion in Lebanon. Israel could take out the rockets if it wanted, but that would mean having to withdraw from southern Lebanon. As it is widely speculated, Israel would like control of the Litani River due to scarce water resources. Also, Israel has succeeded in demolishing much civilian infrastructure. That by itself constitutes a war crime not to mention nearly 1000 innocent civilian deaths- many children. I don't know how much longer a country with the 4th strongest military in the world can garner victim status. It knows that it has spent most of its moral capital from the Holocaust, hence the incredibly aggressive PR campaign.