Having done a lot of research into my own family, I have a number of certificates with such information missing. Also the age of either the bride and groom were sometimes wrong, I would suspect due to age of consent do they want to keep wedding quiet , Hope this gives food for thought.
I feel Anthea, adds some good reasons for lack of information. But it's worth looking at other certificates for information.Davenport, There is a possibility that the lack of the fathers' names were due to illegitimacy or that persons had been brought up by grandparents or as a part of another family (which happened to my own husband). The father could have disappeared years before or deserted the family as in my own Grandmother's case and there are other reasons too. Also, it seems that the Vicar obliged by leaving the entry blank.