Read today's Strategypage article on Lebanon for perhaps the best explanation of why an aggressive, forward-leaning strategy works - as opposed to a "stability" approach favored by others.
Yes, the Israelis made some huge errors. Yeah, they failed to get any of the hostages Hezbollah took back right away.
But aside from some good reviews in the mainstream media, what did Hezbollah get? Well, they fired a lot of rockets for very little effect. They also lost a lot of infrastructure, as many as 700 of its personnel, and a lot of good will among other factions in Lebanon.
Even an attack filled with mistakes and problems is far better than doing nothing. This is why going into Iraq and Afghanistan was a good move. Because even when we err, we do a lot more damage to them than they do to us.