I don’t think that’s all you have to show. In fact I feel like a lot of your examples have missed the point entirely. The point isn’t that there are other ways that could maybe impact the sales or recognition a game gets. This conversation also jumps between copyright and trademark protections. Copyright is about protecting actual assets. You take my assets and make something else with them without my consent, you’ve stolen my work. That’s a bad, immoral thing. Equally ties to the copyright of characters and story. You take the building blocks I’ve made, you’ve stolen my work. Trademark is about protecting brand recogniztion and deals with IP violations.
With that covered, the point of copyright is to ensure the people who did the work get paid for their work. That large or small companies don’t have to worry about someone stealing their works and allowing them to innovate.
So when you say, whatever people will just make another game in the genre, that’s innovation. What if it’s bad? Not everything is good, that’s still positive innovation. You always mentioned large IPs but the truth is that the law is equal and that large corporations are already taking people’s work without asking. We do not need more of that.
For fan made games, there isn’t a huge point to do them without the blessing of the IP holder and you might point to large studios vs small fans but think of it in every scale. Especially middle to small studios being stolen from. It’s just a fan game doesn’t really hold water when it’s potentially putting people out of business because of the issues I’ve already shown. Imagine if copyright wasn’t enforced and someone just re-uploaded existing games. Where do you draw a line on the charges a fan game needs to make in order to qualify. I can tell you right now 99% of players wouldn’t buy a game on steam if there was another fan game of it exactly but for free. So then you have to draw up all these lines that are frankly unfair to the creators. So just let them choose. Their works belong to them. Not to just people who might like the game.
So I don’t see any point for which a looser copyright law would be overall more helpful to society. We need courts to allow for smaller creators to justify fair use but that doesn’t cover anything we talked about.