I kind of agree. I haven't played every Persona or anything (I only became a fan with 5) but there's also something narratively and thematically satisfying about the personas and Velvet Room design tying all the stories together. If they're going to mix it up though it feels like the time would be Persona 6 since it was being built in a new engine (as was Persona 3 Reload, but that started later and is a remake so unlikely to stray from desings in the original).