That is actually a really bad rule, though you probably are only joking.
There are many examples of short, but very valuable code. Just think about anything math or physics related.
A totally new or even just a very efficient implementation of an already existing algorithm can be gigantic if others need to build upon it.
And many licenses are verbose not because they are complicated in intent, but merely because they need extensive legalese prose to cover against many possible avenues of attack.