It’s always been that way. I am not taking sides here, but the fact is it’s a more modern, feminist thing to write the mother’s name. Why does the woman take the man’s last name? Why are couples addressed as Mr. and Mrs. John Smith and not Mr. John and Mrs. Jill Smith? Or the opposite way while we’re at it? If you want to debate that this is wrong, go ahead, but you can’t really ask where the mother’s name went. As far as I know it has always been the social norm.
It could however be that you are simply noticing that people who had previously (during the last few generations) changed with the times are now changing back to the old way. That’s a good point. There does seem to be a shift in some circles to more conservative norms.