Ramon Kasumi

Kasumi is all pure marketing tactics. Even Soejima admitted her Lady Joker outfit was meant to grab the attention of fans. They pulled this kind of thing with P4G (Marie) and Catherine (Rin.) Its one of their go-to remake formulae. Despite a fully priced "remake," they were never going to add her to the team the way they never added Marie to the team. That would require rewinding the script, giving her a social life with the Phantom Thieves, writing lines and voicing them which is oh, so hard. This is why when she gets a Persona, Morgana shoos her off. They really didn't want to put the work in until the plot was over.