First, this tradition is not practiced by "most" of the families, only the ones who have not invested time to learn Islam.
Secondly, *saying the ayath(s) that ask for protection and prosperity will be more appropriate than holding the quran over the head of the newly weds. * :)
So you mean to say that "Most" of the families have really invested time to learn islam?? Thats a good find out but if its true.
Ppl do say ayats always and not only at specific ocassions. And as i said newly weds do not stop saying ayats for protection and prosperity once wedded.