I totally get what you are saying and that seems to be the general sentiment but personally I kinda liked this new angle. He used the alien franchise to bring a new story focused on the engineers, androids and synthetic life just to get studios to greenlight the budget but I can understand why many would feel it’s kind of con trick as the xenos are almost an afterthought in these flicks and are relegated to playing second fiddle.
The fact that the films are kind of flawed, definitely in the downright stupid decisions some of the “experts” make certainly doesn’t help (cartographer gets lost, the xenobiologist is the first to pet the hissing alien vagina snake, …) but as you say, the world he creates, the atmosphere he builds and especially David make up for a lot.
If you compare them to other franchise flicks like for example Jurassic World, which is an admittedly very low bar, these flawed sci-fi epics are a lot more daring and for that reason, imo, more interesting. Then again, people prolly wouldn’t appreciate a jurassic park flick without dinosaurs so I definitely get why an alien film without xenos might not have been the best idea.
It’s billed as a stand-alone horror story so likely no connections with Prometheus and Covenant.