What is the wisdom behind Tayammum being on two limbs?

Performing tayammum on only two limbs aligns with analogy (qiyas) and wisdom. Applying dust to the face involves submission and humility before God, and the feet naturally come into contact with dust. Moreover, tayammum is specific to the limbs that are washed (the face and hands) and is omitted for the limbs that are wiped (the head and feet). This makes it the most just and complete arrangement. As for the tayammum of a person in a state of major ritual impurity (junub) being the same as that of a person in a state of minor ritual impurity (muhdith), this is because dusting the entire body would involve hardship and difficulty, and would make a person resemble animals.