Probably they thought they had enough gingers already.
She and Mr Lodge are the most prominent 'rents in the comics, so this cannot be a coincident. Mrs Lodge (who incidentally is named Hermione) is the least, alongwith Reggie’s parents; who are basically never seen.
I don’t like that Kevin has taken over Reggie’s spot in the main five; the shows Reggie has his jerkish attitude; but lacks the genuine friendship he has with the others.