I had this same discussion with my wife after seeing the film. It would make their decision to check out the planet and deviate from the original mission so much more believable. It also would take one of Oram's (Crudup) beyond foolish decisions out of his hands.They should have had said that Covenant was damaged to the point where they had to make a pit stop. That they needed some critical resource that just happened to be on the planet forcing them to go down. Or that their navigation system was wrecked and they had the choice of either living out their lives on the ship until the air ran out or hope they get lucky down on the planet. Then when David was brought on board they could have said that he fixed the navigation or something. So many other reasons they could have had the team go down to explore a completely untested planet.
Oram's other ridiculous decision to trust David and look into the egg would have played out better if he had refused to look into the egg. However, whilst distracted by egg chamber, David uses his impressive android speed and strength to rush Oram and hold his head over the egg and say something creepy like 'things would have been so much easier if you just had a little more faith'. Or perhaps in response to Oram's comment that he has seen the devil with reference to David, David could have replied along the lines of 'I rather see myself as something of a creator, would you like to meet my children?' I feel the movie needed to pay off the 'faith' aspect of Oram's character that Scott had taken pain to set up earlier