Question

why did the people prefer sons and daughters in the early Vedic period​

Answer 1

A son will accompany you to the funeral ground, light up the pyre and perform oblations needed for the departed soul to have a smooth journey to heaven.

Even after that the son still has to perform several rites so that the soul of the departed gets enough comfort in the heaven world.

But Hinduism has also given us the solution for those not having sons . Even the sons of their daughters can perform the rites. If not available than nephews can take over. So its not necessary to have sons in Hinduism rather a male child from brothers or sisters or daughters would suffice.