It takes time to make things more concise - whether it be computer programs or letters - and still convey the desired meanings.
Blaise Pascal (French mathematician, physicist, inventor, philosopher and theologian) was the inventor of the calculator and other inventions, wrote the following (in French), from Wikipedia.
French:
Je n'ai fait celle-ci plus longue que parce que je n'ai pas eu le loisir de la faire plus courte.
Literal translation:
I made this one [letter] longer only because I have not had the leisure to make it shorter.
This could be translated as follows.
I would have written a shorter letter but I did not have time.
How might this idea expressed by Blaise Pascal relate to the writing style of John and the final verse of John?