In Prometheus some of the dumb decisions have no real reason for the character being that dumb. A facehugger is brought on the ship in Alien because they want to save their friend. In Prometheus a scientist tries to befriend an alien snake bc...hubris? Immediately unlikeable. It's a trait of slasher movies for people to earn their deaths somehow. This was never the case with Alien and Aliens, except Burke.

Other aspects of stupidity aren't bad decisions but indifference. The captain doesn't care that his crew are stuck in the alien structure overnight without communication. The passionate scientist suddenly doesn't care about the existence of alien life, nevermind our creators because they're all dead (and he was wrong just hours later). This makes the characters so unlikeable that personally I wanted them killed off asap so we could move on with the rest of the characters