I can see where, in the heat of the moment, with sketchy to non-existent intel and a mandate to commit violence against anyone suspected of launching rockets.....it was an extremely poor day to be a group of more than 1 person gathered together in Gaza where an Israeli soldier could see you. (Although IIRC, the beach incident was Israeli return-fire, and they claimed there was a mortar-site somewhere on the beach, while the Israeli boat opened fire on homes along the waterfront.)
That doesn't excuse it, that's not blaming the victim. That's just the reality of armed conflict. It's stupid, senseless, and the people who refuse to allow the situation to change rarely have to pay the price for their stance. It is everyone else who bears the burden. Both sides keep saying their primary goal is the cessation of hostilities, but their military wings as usual have their own goals. Hamas has zero chance of ever eradicating Israeli military capacity to attack them, so their goals are entirely reprisal-based. Israel, while also craving reprisal, does have the more achievable goal of eliminating launch sites. The lack of precision is probably a combination of "it's the safest way for our people to attack" and "I don't give a fuck what happens to Palestinians." Peppering Gaza with leaflets telling people to evacuate their homes is essentially saying "I'm walking forward, and I'm going to swing my fists, and if you're still in my way, it's your fault." So while Israel might not be deliberately targeting civilians, they've sent the message they don't really feel all that responsible for the collateral damage they're causing.
I've never really been able to take the PLO at face value either, because they historically seem to have no control over Hamas, or like Sinn Fein and the IRA of old, the political wing is still ultimately a legitimacy cover for the militant wing and not an independent force for peace. And even if they were, the PLO would basically have to disarm Hamas for any hope of real cessation to hostilities. And even if they did, there'd still be 'cowboys', to use an American term, firing rockets independent of any organization, or other organizations moving in to take up where Hamas left off, and Israel would do what it normally does: retaliate back. It is nearly impossible to break the cycle of violence because both sides are so willing to perpetuate it.
No political situation in the world makes me more depressed than the Israeli/Palestinian conflict, because both sides are so deeply entrenched and, when they're not in open conflict, they're antagonizing each other in different ways, with the settlement accords or lack thereof, gate crossing incidents....It's like trying to build a house of cards in the middle of an active game of pool. Every time you get somewhere, someone comes out of left field and knocks the shit down again, because its foundations, the foundations of peace and co-existence, are not strong.
I can't decide if I'm glad or not that Israel is moving in ground troops. The civilian causalities will be very high, probably higher than the whole bombing campaign. But at least it will, hopefully, be somewhat less indiscriminate.