it is because lawyers and legislators are trying to anticipate the holes and this is not always easy as I just learned. It's not possible to cover everything but we can always amend it later.
Reading a new law usually consist in modifications of other laws. Such as : replace the word here by that word at these places. It's really hard to understand what the document is about if you don't have an idea of the broad picture.

I was more or less serious about the Supreme council since it was the name of the Soviet legislature. But since other countries also use it (including democracies) , I don't see a problem with that name anymore.