Israel's Massive Retaliation
(Not to lump them together, because these were the same mistakes, made independently.)
The seizures of IDF troops were clever acts, proficiently conducted. (I don't like either Hamas or Hezbollah - just giving credit where credit is due.) These acts - in and of themselves - did not constitute terrorism because they were conducted against standing military forces. That may be one reason for the virulence of the Israeli government. It was a dramatic slap in their national face. Humiliate the IDF and you humiliate Israel. If one micro-tactical military defeat is allowed to stand then it calls into question Israel's invulnerability both in the minds of Arabs and Israelis.
Everyone knows this is not about the fate of one or two soldiers. This is about the symbolism, esteem, prestige (or whatever you want to call it) of the IDF. No laughing matter, of course.
Lebanon is not being destroyed as part of a carefully conceived strategic calculation.