Gaming is huge. Absolutely huge. Why do you think that games journalism is not only niche, but extremely niche?
I feel like there's more games journalism journalism than just games journalism,
?
I can't really speak to whether or not its niche in an objective sense (i.e. the readership of games journalism), but it may seem that way because the stakes are so low. Games are essentially just entertainment and the availability of accurate information about them is not nearly as important as information about the functioning of government or the actions of large companies that can impact your life.
It also (like most entertainment media) has a large audience, hence the amount of discussions. And that's what gets people discussing it.
It's the same reason sports journalism is so big online compared to its real world impact. Lots of people are interested in the field, regardless of how it affects 'more important' things.
Can you point me to a single piece of significant reporting on video games, that came from within the "video games journalism" industry? i.e. not just reviews or rumours about upcoming games, but actually breaking a story that holds people or companies accountable for something in a way that had a lasting impact?