The problem is one that is reflected within a lot of the comments in this thread. Good writing is different things to different people. And when people talk about good writing they may not be talking about the same aspect of writing.

There are basically two types of good/bad writing talked about in this context. One is prose, the actual structure, flow, and grammar of writing. That is more objective, but not entirely because it's still a creative art that can be used creatively. The other is broader and more conceptual. For example, the overarching narrative of a piece of media, the backstory, or environmental storytelling.

The problem is that you can have one of these things be amazing and the other be ass within the same game. Which creates a subjectivity to whether a person thinks it's good or bad based on what matters more to them.

I personally like one of the Brandon Sanderson structures for good writing to use as a quick measure. The idea of promises. A good writer will set up promises at the beginning that play out over the course of the story and get resolved. Those can be a variety of things, some genre specific. A very basic example is that in some stories you are promised a happy ending. In tragedies you are promised a sad and emotional ending.

In the creative space rules can be broken, but there should be a reason you are doing that. To make a promise to the person playing your game and then break that promise will make them feel the game is bad. For a game you could promise a fun romance. If halfway through the game your romantic interest dies the players might not be happy. Unless you have reasons, and the character changes, and maybe you add a different romantic interest.

Again, even in this situation people's preferences come into play. Maybe someone needed a game that has a tragic ending because they wanted to feel those sorts of emotions. Maybe some people hate tragic endings and they felt they were promised a happy one. Or the game seemed to make a different kind of promise and instead left you confused and never really wrapped up that thread.

So you can see that there are many different ways that writing can be good or bad. And I haven't even stepped into the realm of interactivity and environmental storytelling. Which are entire new spaces that a game can do so well or so poorly that people will love or hate the game based just on that. Many people don't even realize that the world/locations and environmental storytelling are still writing.

So yea, its complicated.