You mean like your phone is in your pocket, you hear it ring so you pick it up and put it to your ear and it answers? How would the phone know the difference between that and if you put it back in your pocket?
Haven't you had a phone with a proximity sensor that when you have a call you put it to your ear and it automatically answers? Most of the other manufacturers have had this for a long time. Samsung never has. A heck of a lot easier instead of putting your finger to the answer button.