I understand the concern about Sims 4-style DLC fragmentation. I also would not want inZOI to end up with isolated systems that do not connect properly with the base game.
But I do not fully agree that DLC should never introduce gameplay. I think there is a difference between locking a basic core system behind DLC and making a deep optional expansion for a specific playstyle.
For example, general fame, reputation, social media, performances, schedules and career improvements should ideally be useful in the base game too. Kjun’s roadmap already mentions K-pop and stage performance content, including stages, themed environments, idol styling, K-pop dance/performance motions and superstar performance events:
https://forum.playinzoi.com/t/topic/8256
But a much deeper idol-focused system with agency rules, trainee-to-debut progression, comeback promotions, fan signs, dating scandals, variety shows, paparazzi and idol dorms could be big enough to justify a DLC, especially if not every player wants that kind of intense idol gameplay.
inZOI is currently still an Early Access game sold at a discounted price. I do not think we can realistically expect the developers to keep expanding every large gameplay fantasy forever while keeping everything inside the base game price. A DLC can also help fund more specific systems for players who actually want them.
To me, the best solution would be a hybrid model: shared foundations in free/base updates, and deeper optional career expansions as DLC. That way the base game still improves for everyone, but players who want more detailed idol gameplay can support and access that extra depth without forcing it on everyone.