Atlus are getting pretty bad with DLC, like how all the bonus cosplay costumes in p5 are paid, unlike being ingame unlocks like p3 and p4g (at least they come with battle music) but the biggest sins are the dlc personas. Firstly, as they're fused like normal personas, they can interfere with normal calculations. Iirc Satan or Michael is unfusable because Messiah interferes and always comes out instead of them so you have to deliberately do complicated fusions.
Despite this, they're fine as this as they're just OP fanservice and you miss nothing without them. All except one, joker's 3rd tier persona Raoul, which is scummy to hide behind dlc