Nothing can justify the killing of innocents, by either side. The fact remains that if Hamas didn't hide munitions in schools, moseques, and hospitals, Israel would have not even a semi legit reason to target them. And that is what gets me, Israel is using a proven military tactic. If you can you try to wipe out any enemy weapons stores you know of, and that is what they do buy bombing such places. I don't defend they're killing the innocents they have, but to speak out against what they're attempting to do in reality feels disingenuinous to me. The killing hurts my heart, and I can't help but think the deaths are just as much the fault of Hamas as they are the fault of Israel.
Historically speaking, those kinds of tactics don't work on terrorists (ample evidence of that from the responses due to the IRA in the UK and ETA in Spain) because it's pretty much impossible to get them all. Even if Israel basically destroyed every single building in Gaza, the terrorists would come back in a few years after re-arming themselves. And you'd be right back to square one.
What's worse though, is that by killing so many civilians, you pretty much guarantee that a new crop of Hamas terrorists will rise up against you. So basically this is a terrible long-term strategy.