Well, then I'm left with two copies and I have to go back and delete one. If OSX had a cut/paste, that might work better. Even so, with the way Finder currently works, it's easy to have 10-15 Finder windows going at any moment, so cmd+` can be a pain.
It has copy/paste for files, but you can't "cut" a file. This is a continual source of frustration for Windows power users who come to the side with cookies. My guess is Apple doesn't think "cutting" a file makes sense: you are actually moving the file or deleting the file. However, why it would suddenly make sense to "copy" but not actually have "copy" do anything is still confusing to me.
Why wouldn't you just use copy/paste?