Discretion of a human judge is grease on the gears of law.
Moreover the content and legal rules predetermines what will be written in such legal documents down to the phrasing. While there will be differences, it's not "free writing"/"express yourself" kind of thing.
To me it seems this would make things much clearer to parties involved, and reduce opportunities for abuse compared to many pages of boilerplate and only a few lines that matter.
That said, a lot of state law is kind of like what you describe. An initial law, and tons of differences applied on it. E.g. article 3242 clarifies article 432 and adds the provision to do so and so.
Two disclaimers. First, IANAL. Second, "standard" really means "a lot of people do it this way", not "this is recognized as the right way to do it".