Why didn`t they take on the female form as well as the male form ,then their offspring would have been super heroes..... or not..
S3: in the story, it is assumed that sexual pleasure is more intense, guaranteed for the male, not always for the female. So the angels went for the orgasm.
It is telling, that the fallen angels did not fall for boys. although guarantee is there too, I assume. ask a priest.
The pre-deluge heavenly pregnancies were not the last ones, of course, later without intercourse even.