Why does using the proper definition of words matter? I think that should be fairly obvious.
"Downloading copyrighted music is murder."
Ok, then downloading copyrighted music should be punished like murder.
Oh, it isn't Murder?
Well, it also isn't theft. So it shouldn't be punished like it is theft or treated like it is theft in conversation. It should be punished like and treated as copyright infringement, which it is.