There are many reasons you might want a tracker apart from recovering a bike from a thief. For example, you might be flying somewhere with the bike, and it is nice to know it is getting put on the right airplanes, etc. You might stay in a hotel where they make you put your bike in a luggage/ski storage room, etc.
Also, if someone grabs your bike, they might not have time to hunt down your tracker. They make a water bottle cage that hides the air tag, which could help also.