If you just walk towards them relying on PC Armor to let you go first, it's unrealistic you wouldn't see each other and both sides be somewhat prepared.
Try that in the previous games. You'll find that the enemies will make their moves if they spot you before you start shooting at them. If, however, you get to start combat on your terms (which can't happen unless you've spotted them but they haven't spotted you, which
realistically should give you a big advantage) there won't be an omnipotent referee going "Hold on there fellas, this just isn't
fair. Everyone gets to take five minutes to prepare themselves now." That's just stupid. The situation where every member of your group takes their turn shooting the unaware enemies is an abstraction of them all shooting at the same time, exploiting the element of surprise.