It's just disappointing that, with so many talented writers, they seemed to--much as with Prometheus--fall back on some really basic, skimming the surface plot elements. I think it's the direct product of too many cooks in the kitchen (and Scott being unclear about what he thinks and wants), and what we got with A:C was entertaining and had some effective bits, but ultimately diluted what could have been a fascinating narrative and undermined the entire film that came before it.
I'm sure at some point there were treatments and pitches to divide David and Shaw in space with another crew, either with the Covenant colony or a team looking for evidence of what happened to the Prometheus, and they were vetoed because the film might feel choppy or something. But isn't that what a great director is for? The flashback sequence in A:C was fun to look at, but it still looked sloppy and shoehorned. And leaving it out would have been even worse. Making the Shaw/David story a real part of the fabric of the film would have solved this.
If they agree to make one final film, I do hope they allow ONE writer to really figure out how to make the pieces fit together in a way that makes a bit more sense of what's been put out there and advances us forward toward the original film's timeline (or beyond).
