Let's go with your example then: rape. Who cares why people rape, right? It's a criminal act, so we should just shoot those who commit it. Well, for starters, knowing what general factors lead to rape occurring can help policy-makers and law enforcement in predicting and possibly combatting its frequency. Also, a person committing rape because it gives them a feeling of power is a very different indicator from a person committing rape because the victim looked so hot and was just irresistable. Only in the second situation would a victim's choice of clothing possibly have had anything to do with leading to the rape. (And before anyone tries it, no I'm not saying we should blame the victim. It's just an example of what difference motivation can have.) Or how about drug use? Why people use drugs is a pretty damn good indicator of how the DEA and State agencies can properly combat its use, predict where potential buyers will crop up, and what type of criminal response scenarios are likely to involve suspects who are high. I think the fundamental difference, though, is that your attempt to dismiss the motivations behind criminal acts, or to say that their motives don't matter, is an attempt to put a false barrier between "them" and "us". If we ignore the motivation behind crime and only react to crimes, "they" are just going to continue appearing among "us".