The two that were stolen at my former employer would fall under the stupidity category. Engineers leaving their laptops in their cars in plain view.
Exactly. Like I said, it CAN come in handy, but IMO it'll either be taken by someone who knows what they're doing and LoJack won't be able to track it (disassembled and parted out for cash), or the theft could have been easily prevented by common sense. If you have something valuable, be it a computer, phone, watch, jewelry, etc.; don't let it out of your reach (even just being in your sight in a public place doesn't cut it). People that leave a laptop sitting in a car make me laugh - is it really that hard to leave it in the trunk or at least put it on the car's floor covered with a sweatshirt? If people don't think there's anything valuable in the car, they're far less likely to break in.
I was looking up Kensington locks the other day for the added "convenience," but decided against it. If someone's really determined to get my stuff, they're get around the lock (bolt cutters are relatively easy to carry / conceal, and I find that onlookers would rather keep their nose out of the trouble than actually say anything), or if they're really determined to do harm to me in some way, they can just deface the locked-up laptop anyway.
The moral of the story is, if you value something, simply don't give others the opportunity to take it from you. There's absolutely no better security plan than that.