A ground invasion of Gaza is a bad idea. The temptations are many -- Gaza is controlled by an anti-Semitic Muslim fundamentalist organization committed to Israel's destruction, and it obviously harbors many men who are actively plotting ways to kill Jews. But there is no military solution to Israel's political problem in Gaza, short of some sort of World War II-style Tokyo campaign, or Putin-style Chechnya campaign (or, for that matter, an Aleppo-style Assad campaign). If Israel were to go into Gaza, and get lucky, it could avoid creating masses of civilian casualties. But the Israeli attitude, after the Jenin experience in 2002 -- in which soldiers lives were lost precisely because the army, for humanitarian reasons, chose not to bomb the Jenin camp from the air -- is that it will not put its soldiers in undue harm simply to avoid creating the civilian casualties that the cynics of Hamas hope they would create (and work assiduously to to help Israel create).
Israel does not have the freedom of action to wipe out Hamas's armed wing (plus the armed wings of other groups that may or may not fall under Hamas control or influence). Plus, it shouldn't lay waste to Gaza, both because this is immoral, and because Gaza will, the day after, still be Israel's neighbor.
The air campaign against Hamas rocket sites is understandable and defensible. A ground invasion will lead to misery and woe; to a total rupture with Egypt; to a further loss of legitimacy, and thus, deterrent capability -- and, at the end of the day, does anyone actually believe that Israel would be able to fully neutralize the Hamas/Islamic Jihad threat? These groups might need time to rebuild, but they would be rebuilt. And then what? Another ground invasion?
Now is the time to try the Egypt card. As Meir Javedanfar writes:
...(W)e should... engage the Egyptians. Instead of invading Gaza and pushing Morsi into Hamas's corner, lets continue to make Hamas his problem. An invasion will not be in Morsi's interests either. He has enough economic problems on his plate. With a major economic problem on his hands, he would prefer not to anger the Americans, and the EU by being seen to back Hamas.
So lets get the Egyptians to start a massive shuttle diplomacy to rein in Hamas attacks. If they manage to do this we in Israel will have averted a war and all its costs while Morsi could say that he is now the biggest power broker in the region.
If someone could plausibly make the argument that a ground invasion represents a long-term solution that both avoid large numbers of casualties and enhances Israel's international position, I'm all ears.
In the meantime, perhaps Israel should contemplate actually moving the Palestinians down the road of political independence on the West Bank, under moderate, far-seeing leadership. This might convince the people of Gaza that Hamas does nothing for them. Of course, there's no sign Israel's leadership takes seriously the need to create conditions on the ground necessary for the establishment of a Palestinian state. So here we are, again.