The fruit of the Enlightenment has been the growth and centralization of the state, at the expense of all other institutions. The material plenty we enjoy today are in spite of this change, not because of it.
In a relatively unhampered market, a declining population is not necessarily an economic problem. But in a system where retirees can loot younger workers through government pension systems, there is a real problem, indeed.
Angela Merkel has caused cultural blowback with seemingly unchecked migrant flows while simultaneously harming business with higher taxes and more anti-business regulation. The results have not been great.