The Battle Ragers patrol East Road regularly, and it is probably the most patrolled area in the Granaak Box. Therefore it is only logical to find a potential mage corpse in East Road.

My counter question to you and Yhorian is: How would you make exploring roads and other not obviously magey areas worth exploring if you wouldn't plant the preps there? The point is that those are exploration rewards that are rewards for careful explorers. A person enjoying thorough exploration would find such corpse. A person with no love for exploration who only wants the wands for powerplaying would not. Personally, I think it's a good thing. There should be rewards for people who actually like to explore to make it more worthwile.