Death and identity

In 1793, as it just overtook power in France, the new government decided to open the tombs of the French kings in Saint-Denis and throw a thousand years of history into a pit as a celebration of their victory.

In 2001, the Taliban destroyed the two gigantic Buddhas of Bamyan, erasing 1400 years of historical significance with a few kilograms of plastic.

Now I wonder; why putting so much effort in erasing their own past, if their position in their present time was accepted, justifiable and welcome?