Beyond the practical advantages in our context you mention, though, in some cultures it’s just traditional to do the main celebrations on Christmas Eve.

I know it’s largely the case in Scandinavian countries (see here: https://scandinaviafacts.com/norway-sweden-denmark-celebrate-christmas-24th/) and I suspect other parts of continental Europe.

EDIT: I’ve found multiple mentions that in Italy it’s tradition in some families to open gifts on Christmas Eve. There is also a tradition of a 7-course fish meal on Christmas Eve.