Why does God inflict punishment?

God inflicts punishment for the sole purpose of bringing the embodied being back to reason and making them realize their error. Punishment, or chastisement, also allows one to erase the sinful act committed in their past life, to perform penance, to show repentance, to resolve never to repeat it again, and to turn to Krishna, God, the Supreme Personality.

Why do worshippers of Shiva enjoy such material opulence?

Material happiness and wealth are synonymous with pleasure of the senses, and more specifically of the genitals, the tongue, and the mind. Through the action of thought, we invent many objects aimed at satisfying the genitals and the tongue. In this world, material opulence, happiness, is measured according to one's sexual prowess and the delicious foods available to satisfy one's needs. The material progress of civilization requires the creation of new objects of pleasure, all focused on sexual and linguistic pleasure.

The opulence of Siva's devotees is merely material.

Indeed, such pseudo-progress of civilization represents the very cause of entanglement in material existence. Is this progress?

It would rather be degradation. In other words, the blessings conferred by Siva cannot truly be beneficial to the conditioned soul, although they seem to sweeten existence by bringing opulence.

Why did God create the four social divisions and the four spiritual orders?

The Lord said: I have created the four divisions of society according to the three gunas (the three attributes and modes of influence of material nature: virtue, passion, and ignorance), and the duties they impose on man.

Truly, spiritual education, charity, austerity, and truthfulness are the four pillars of religion. To enable humankind to acquire these sublime qualities, God created the four social divisions that correspond to the vocation of each being within society, and the four spiritual orders, which lead to spiritual elevation and Krishna consciousness.

This is the natural organization of human society, the perfect form of social organization, which aims at the material and spiritual well-being of human beings. It is made up of (4) four social classes according to the functions fulfilled by its members, and of (4) four spiritual stages of life.