For a device with GPS, several unique identifiers, & constant connectivity, there's no reason why an iPhone should be able to be stolen and used for anything by anyone but its rightful owner.
Logging into iCloud should not only present the find my iPhone GPS feature, but allow you to reroute all incoming communications to the web portal, have it alert you when the device comes online or auto-record location tracking & whatnot, give you the option to monitor the iPhones cameras & mic, record discretely, and prepare it as an easy package to hand to police. Police won't usually bother with recovery of a stolen phone, but if they don't have to hunt for it, and can see/hear/record the thief with the goods live, it makes for an easy recovery. Looks good at the end of a month. ...especially if it was stolen with a car or other items. iCloud should be the total control portal for your devices.
find my iPhone is pretty inconsistent sometimes or else i'd be in the middle of the atlantic ocean every once in a while, plus its not that hard for a thief to turn it off and restore it ...