The Mütterrente is a good idea, because it rewards having children which end up paying the pensions. This leads to sustainable population replacement. If anything, this should be expanded to fathers as well (I don't mind mothers receiving more).
What's not such a great idea is paying the Mütterrente retroactively. Pensioners can't have children retroactively to stock up the tax base, so all this does is increase the tax burden for the current generation, which discourages them even more from having children.
What's not such a great idea is paying the Mütterrente retroactively. Pensioners can't have children retroactively to stock up the tax base, so all this does is increase the tax burden for the current generation, which discourages them even more from having children.