sometimes they come in right and dont effect your other teeth and you can keep them... but usually they press against your other teeth and it causes your teeth to shift which you dont want to happen, so thats why they pull them
honestly its a very simple procedure, and it doesnt even hurt. i have slight discomfort from a little swelling but its not bad plus you get pain medication so that helps. To be honest the most annoying part for me is my tounge and lips being a lil numb still haha