Why do you consider them very important (respect the sacred place and honour your ancestors) ?

Them? Are you talking about ancestors? Here are some factors why it is important to keep in mind and honour your ancestors.

To determine the birth parents of an adopted child. Alternatively, to find children given up for adoption.

Proof of Paternity - To determine the biological father of a child.

Religious Tenet - To satisfy the tenets of the religion. The most notable example is the Mormon Church (Church of Jesus Christ of Latter-day Saints).

Community History - To document a community history by understanding the families that founded and influenced the community.