Indeed, They do have a heavy launch constraint due to the impossibility to launch westward for fear of first stages falls and crashes in neighboring countries. Launching westward against earth rotation is a heavy toll on the capabilities (mass). Thus leading to bigger booster studies… A
Yup. Israel is kind on wrong side of Earth rotation. Kourou, The Cape, Baikonur: optimal launches are from west to east (say, from America: in the direction of Europe, or from Kazakhstan: China, North Korea: Japan, and on, and on). But if Israel launch this way, spent stages would fall over Jordan, Iraq, Iran, Russia... oops, not exactly friendly neighbourghs.
Dumping spent rocket stages won't improve troubled relationships. Even less if a failing rocket dumps an Ofeq spysat on, say, Iran. Yiiikes !
And so they launch the opposite way (in the direction of, say, Greece / Spain / Europe: over the Mediterranean sea) and take a huge penalty...