User blog comment:B214/Shin DxD 1 discussion/@comment-2601:340:C501:C683:D9E9:7B80:4551:9FCA-20181113211020/@comment-33341107-20181118152141

If he becomes a maou he is of a higher social standing than a head of a clan. Rias being the head of her clan is also a position she hold only for a time, like being a maou, the key difference is if Issei is a maou he'll influence all of the underworlds society and probably the societies of other factions since their all at peace now while Rias will be in charge of a part of the underworld. He would be of a higher social standing if he becomes a maou.