It might be a strong worker, but that's not much help when it refuses to work. Stubborn, intractable and often bad-tempered, the mule isn't such a terrific new model, after all. Changing the Torah and making it more fashionable, aside from preventing its perpetuation, is never really an improvement anyway. Hashem made it the way it is because that's the way it works. The Torah is perfect, and perfection cannot be improved.
Any modifications can only detract from it.
That which is perfect does not need improvement. And once man adds to the Torah, he shows that he considers it to be in need of alteration, which is the first step on the path to essentially reforming it according to his whims. This lesson is especially important for the leaders of the Jewish People. Although placed in a position of power, they are to remember that the salt of the Jewish People doesn't need preserving, and any attempts to alter it are harmful and forbidden. King David has made Shlomo king . . .