Yep, the writing is mostly black and white and pulpy for a reason. It's trying to drive home it's true message and themes in the periphery while giving you people to root for and something to look forward to. Persona 5 is the jrpg equivalent of a pulp hero novel/film. If you need any more convincing, remember how the writers chose to express Ann's character through her interest in the villainess character she looks up to. If the villains were given too much nuance, the central idea of people being wronged by society rebelling against injustice wouldn't be clear. If the writing was any more realistically bleak, it would be too depressing and the game would lack a motivating factor to play. The villains of Persona 5 are not only exploitative and morally bankrupt, their evilness is the way it is because they are also not true to their own self. Their values and desires got twisted by society. The goal of the game is to inspire the player to consider and address social issues in our society, to have conviction in your values, and to stand up against injustice when you can.