Chullin 118: on Handles and Protective Appendages

The Gemara quotes Massechet Okatzin (1:1) to teach us further about the differences between adding to a piece of meat so that it becomes large enough to be ritually defiled and not being able to do so with an animal found dead in the road.  

It teaches that if something serves as a handle to a bulk but not as a protection, the attached food becomes ritually impure if the handle comes in contact with a source of impurity.  The handle then transmits ritual impurity but is not included in the amount required to make up the necessary size of an egg bulk to demonstrate the impurity.  

It goes on to explain that if something serves as an appendage to the meat that is protective, even in a case where it does not serve as a handle, the attached food becomes ritually impure if the protection comes into contact with a a ritually impure item.  The protection imparts ritual impurity and it also joins together with the meat to create the required measure to impart ritually impurity.

When an item does not serve as a handle nor as a protection, the attached food does not become impure even if the appendage comes into contact with ritual impurity.  The appendage does not impart ritual impurity nor does it join together to constitute the measure required for the meat to impart ritual impurity. 

In the end we learn that the handle which allows the object to be picked up or used may not supplement to volume of the meat.  However, if someone were to pick up a dead animal by its bones, hooves, sinews, or horns, they would be considered to have come into contact with meat that has been ritually defiled.

One has to wonder about why these rules exist.  Was the intention to keep people from being in contact with found animals that had been killed?  I am clearly missing some pieces of information that would help to explain the purpose behind these halachot.