While I acknowledge that naivete may result in pickpocketing and theft, it is important to remember that the victim is still the victim, the perpetrator still a criminal, and a location like Barcelona* is lax on petty crime. Perhaps the Barcelona police would be more attentive to this issue if tourists did stop going there because of its reputation as a pickpocket friendly

*Barcelona is being used an example, because it has been mentioned many times on this thread, but you can insert the city of your choice.