There is real fear that Israel will succumb to international pressure, and not finish the job in Gaza. Hamas is an irreconcilable enemy of the state of Israel. It will not soften its position because diplomats scurry about. When there are temporary ceasefires, the story is always the same:Hams rearms and strengthens for the next battle. They need to be defeated, not weakened.
A few writers take on the disproportionality issue. War is not golf, and there are no handicaps. One side starts, the other responds, and the goal is to win, not jut hurl back exactly what was received from the war's initiator in the same proportions. For the record, as Alan Dershowitz points out, Hamas is guilty of many war crimes.
Other views (I am not an equal time, fairness doctrine person, but other points of view are worth viewing). I am not a military person, so I am the wrong one to propose or critique military tactics. However, I think there are some lessons from the Iraq war that are relevant.
Whatever your views on the wisdom of the Iraq war, at this point it is pretty clear, that Iraq is not a threat any more to its neighbors -- whether Israel, or other Arab states (Kuwait) or Iran. Strategically of course, Iraq was a counterbalance of sorts to Iran before the war.
Iraq is not a threat now because there was regime change -- in terms not only of leadership, but type of regime. The country has been a mess in terms of its politics since 2003, because vacuums are created when fascists are deposed, and it is messy until a new balance that is stable is established. So long as Hamas remains in Gaza, and the mullahs run Iran, Israel, and many Arab states will be challenged constantly by Hamas, and Hezbollah and Iran.