Actually, dramna , this law is very old made by hamourabi in baybalon.
but let us think logically about

this law was made to prevent the EXCESSIVE REACTION by the family of the victim.

especially for tribes.

for example when you know that arabs before the coming of the prophet by 50 years or something, she kept fighting for 40 years for a camel,and a lot of people died for that reason and another series of battles occurred for killing a man