SPOILERS--
Landing on a completely unknown planet which supposedly has same environment as earth with no experimentations... might as well not even put our protective suits on
Carelessly touch strange objects and not be vary of things you've never seen, not telling others that you might've inhaled something weird, this isn't some trip to a forest on earth you are familiar with...even there you have to be careful
See a robot who is trying to communicate with the alien who killed a crew member , be suspicious, now whom you can't trust , leading you to a nest of things that killed your crew but you still stick your head out to fall prey
Even if Dr. Shaw was able to rebuild david he was just left with a head at the end of prometheus and they were stranded on an alien ship with different technology and different approach to things
How the hell did they/he manage to have him back to how he was initially... And yes.. David is very optimistic that Someday someone will come and complete my "perfect being"
The updated robot walter was thrown out so easily from the film and they never completed the scene how he kills walter , what really happened to elizabeth shaw and what was it that caused the Engineers to fall victim to whatever happened to them because of the spores of parasites
And most of all they prepared for the mission for over a decade to reach origae-6 why would the crew abandon the mission over a rogue transmission