Plenty of people who work on cinema out there and many of them have made shit movies. Plus there are critics who gave the movie a rotten score. I don’t know about the book but there’s so many unanswered questions in this movie because a lot of things don’t make sense to me.
Mystery =/= bad writing. If you don't like unanswered questions, though, best to avoid 2049; it does a good job of not ruining the mystery and ambiguity that helped make the first film so discussable.