I think what happened was similar to the development of the recent Mad Max movie: producers assumed that most viewers would be young and would know little about the first Alien movies. Thus, a movie was produced that would retell the story to them using elements from the first movies while appealing to their sensibilities through stunning visuals and dialogue that reflected their ethos, which included more discussions on characters' personal views, etc. The result is, for those who saw earlier films, a rather ordinary work.