I saw this yesterday, and yeah, I felt like it's very hard to swallow "I like to frustrate players with ambiguity" when so much of this game is obviously incomplete. There is a huge difference between leaving your audience wanting more by "frustrating them with ambiguity" and leaving your audience sad and disappointed because it doesn't make sense that there isn't more.
I know that Patrick Mills wrote both Dream On and I Fought the Law, and I think they're good examples of what I'm talking about...I can accept that we don't have a definitive ending to Dream On, because we're fighting a powerful, shadowy organization, and at least one of the people we're trying to help doesn't want us to interfere any further. With I Fought the Law, however, it doesn't really make sense that we just drop the investigation at that point, River seems like he wants to take it further, I'm sure that the Peralezes would be happy if you brought down Holt, and just ending there it feels like yet another example of cut content.
I actually do like ambiguous endings in some instances, but sometimes the story ends too soon or in an unsatisfying way, and just telling us "it's ART" doesn't work for me. If your purpose is to be provocative, ending your art with a tepid, confusing finale isn't daring, it just makes us think that you ran out of time or couldn't think of anything better. And with Cyberpunk 2077, knowing how much is still unfinished in this game, ambiguity just seems like another excuse.