Jewish sages said: "Whoever has compassion for the cruel will eventually be cruel to the compassionate" (Yalkut Shmuel 121). This is a much-quoted saying in Israel. Israeli judges don't seem to buy into it. The newspapers regularly tell us of convicted offenders getting ridiculously light sentences for terrible crimes. I really do believe this is a result of the judges' compassion (which is commendable in itself, although maybe I’m just being naive), but they don’t seem to have compassion for the victims' suffering, or for potential future victims, in their sentencing.
One result of this leniency, I think, is the affect it has on Israeli law enforcement agencies, which some may say are disinclined to exert themselves at the best of times, in anything but matters of national security (i.e. fighting terrorism). This could be a result of low pay, long hours, job security and being chronically over-worked, but I do believe frustration at the seeming ineffectualness of the courts plays a part in this, too. If you've worked for months, long and hard, on a big criminal case and the judge gives the felon a six-month suspended sentence, you'll be disinclined to put in so much effort next time, won't you? And you will eventually become desensitized and stop caring.
I think people tend to blame the laxity in which Israel deals with severe crimes committed by some fanatic Jewish West Bank and Gaza Strip settlers on government policy. I think it's more down to the indifference of law enforcement agencies and their consistent desire to avoid trouble. And the fact that courts tend to treat settlers, who have committed crimes against their Palestinian neighbors, extremely compassionately.
But it's so terribly, terribly wrong. It must change.
Update: Lynn B. has the reaction of Yesha (Judaea, Samaria and Gaza, i.e. settlers) Rabbinate Committee to the olive tree uprooting. They strongly condemn these acts and call for the prosecution of the perpetrators.