‘Metadata’ refers to the information surrounding a story, rather than information within the story.
This is, despite what some might think, still extremely important to the story.

It’s become a trend recently to analyze stories in a vacuum. That is, to ignore the context into which it was released, who worked on it and even whether it’s an adaptation or not. This is an erroneous approach to analysis/critique, as you cannot meaningfully strip all context from a story.
Now some might argue that not all context is being stripped, but then you run into the issue of ‘how do you determine what context is/isn’t important?’.
To give an example: you cannot meaningfully analyze a sequel to a story, because it’s a sequel. Sequels are written with the presumption that the audience is familiar with the previous entry, which means that there is a smaller need to explain things. If we analyze the sequel in a vacuum, we immediately notice that it’s assuming the audience is familiar with information that isn’t present in the story…which is an error.
Just think about the absurdity of criticizing a sequel for not introducing the protagonist because that happened in the previous entry.
This is why the metadata has importance to the story that’s being told: which includes the title and its relations. Now, in regards to the question ‘How do we determine what context is/isn’t relevant?’ I think the answer is to look at how closely related things are. Sequels, adaptations, shared crew, etc.
All that said, I don’t actually think there’s an obligation to look at every angle of something. It’s entirely fine to criticize a film adaptation of a book without having read the book. But there’s a big difference between saying that you aren’t familiar with the original, so you can’t comment on it and saying that the original doesn’t matter because stories should be analyzed in a vacuum.

Since I mentioned titles as being important, let me explain it here in a sub-section: the title of a film is very important as it conveys important information to the audience, which then acts as part of the unspoken agreement between audience/creator.
For example: Terminator 2: Judgment Day. What does that title convey? Well, first of all, the number ‘2’ conveys that it is the direct sequel to the first terminator. Second of all, the subtitle ‘Judgment Day’ signals that the in-universe event, Judgment Day, is going to be relevant to the plot of the film.
Now imagine you walked into this film and, instead of being Terminator 2, it was just the plot of Die Hard. At that point it doesn’t matter how good the film you’re watching is, because it lied to you: it isn’t Terminator 2, it’s Die Hard.
This is why titles and subtitles are actually pretty important and should be considered when criticizing stories. It’s also why I take issue with some titles like: ‘Girls’ Frontline 2: Exilium’.