The governmental order was structured to produce man possessing free will — and everything is laid down in Keter.
The Sefirot are exactly the configuration the Highest Thought required to produce man with free will. Nothing is arbitrary; everything is calibrated.
Op. 14 opens a new section unit (the Fundamentals, Op. 14–17) by asking the most basic methodological question Klach has yet asked. Why this many Sefirot, arranged this way, with these particular interconnections? Klach's answer becomes the structural-philosophical anchor of the rest of the book.
The Highest Thought (HaMachshavah HaElyonah) calculated exactly what was required to produce a creature with intelligence, with a good inclination, with an evil inclination he can master, capable of moral service, of earning merit, of being corrected by punishment, and ultimately of receiving the eternal reward. The Sefirot are exactly that many, arranged exactly that way, with exactly those interconnections, because no other configuration would produce that creature.
The analogy Klach uses is a craftsman who needs fire of precisely moderate heat. Put one piece more wood on, and the fire burns too hot. Put one piece less, and it does not burn enough. The exactness is not arbitrary precision; it is the only way the goal can be reached. The same is true at the cosmic scale. The cosmic government has its specific number of Sefirot, its specific arrangement, because the goal — man with free will, capable of earning the bestowal — required exactly this and nothing else.
The Midrashic anchor is Bereishit Rabbah 12:1: "a man should not say, 'if I had three legs…'" The point is that complaining about cosmic structure is incoherent. The structure is what it is for the goal it serves. A different structure would mean a different goal. The cosmos as it stands is the cosmos required for the bestowal Op. 3 named.
And the first light, in which the reason for the whole is embedded, is Keter — the Crown. Keter is the architectonic foundation. The reason the cosmic plan has the shape it does is rooted there.
Op. 15 will sharpen this by showing that Keter is bound up with Eyn Sof — about Keter it is forbidden to ask, while from Chochmah onwards it is a mitzvah to investigate. The exactly required doctrine of Op. 14 returns operationally throughout the rest of the book, most pointedly at Op. 116 (CHaDaR's three-column structure runs through Zeir Anpin (Z"A) because this is what is required for the cycle of six thousand years) and Op. 138 (the eight-stage Coupling order is the operational form the cosmic plan requires for human service to integrate into the cycle).