Most of the Israeli shells are just fired at open fields, in order to make the appearance of doing something.
This is the equivalent of Chamberlain dropping leaflets on Germany during the first months of WWII.
It accomplishes nothing and permits the offenders to continue their operations as usual--with even more contempt for their opponents than before.
If Israel would decide to use counter-battery fire and immediately shell the launch sites, the Gaza residents would in turn force the end of the launchings.
A few innocents in the launch areas would die, but that's the price they pay for deciding to back war. (Bombing factories in WWII killed civilians, also, but that's the price they payed for deciding to back war.
As Gen. Sherman said, the South chose to resort to war, and so could not complain when it got war.)
Quote from The Prime Minister of Israel