Now the way the accounting worked, every songwriting credit counted as one “share” of the royalties. Without this short song, Waters would have gotten 3/4 of the songwriting royalties. By including it and splitting it in half, he got 5/6. Was it a purely artistic choice? We will never know, but as the story goes the resentment between the two eventually snowballed and the band broke up.
The software analogy would be source code = melody and lyrics and compiled/deployed software = sound recording, but the analogy doesn’t hold in that it’s easier to replicate compiled/deployed software from its source code.