Comment by gchamonlive

That's because the hero's journey is an attempt to study the physiology of story telling, so it's not restricted to the typical written romance. Games just like books and movies are often trying to tell a story and it'll eventually follow Campbell's book, even if unaware or not trying to.

I'd say that writers do know about this a lot, the problem is that games are becoming progressively more expensive and riskier to make, so money will push new titles to be safer and more boring, which could be why you perceive them as unaware of this, because why not wouldn't they want to make a good game?