This seems unnessecary. Besides, while it may look like everything happens in a split second to you, the dwarves are operating on an accelerated time scale so that animal may have taken hours or an entire day to process.
So its ok to imagine the butchering happened off screen (and in a split second) when it comes to your tame animals, but not when it comes to other animals? This unnecessary idea is already in the game. When I kill a wild deer with my military, a dwarf has to go and haul the corpse over to the butcher shop. Then my butcher has to stand inside the butchers shop, over the corpse, for a certain amount of time before I can get the meat. This makes sense, animals don't just explode into a pile of meat when you kill them, you have to work for it. Chop them up before your dwarves can come and haul the pieces away.
Yet when it comes to tame animals, they do explode into a pile of meat. No butcher necessary. Why?
Another thing, let's say you want to start a Fort where Meat is your main industry. There are two ways to do this:
1)embark with a bunch of cows, horses, dogs, cats, whatever. Wait a while so they can breed and now you have a ton of animals to get meat from.
2)embark with hunters, crossbows, and tons of bolts and hunt for your meat.
In option 1 it doesn't matter if I take a proficient butcher along. Meat is instantaneous.
In option 2 it makes a BIG difference if I bring a proficient butcher. He has to work and work fast or the next kill will rot while hes busy with the first.
How does that make sense? An animal is an animal no matter where you get it from.