You have absolutely no guarantee of getting 2 ENCRYPTED engrams which are the only ones worth getting OR getting 3-4 end game roll rewards which is a rare occurance. A lot of times you will get shaders that you already have or two already decrypted blues that aren't worth the time it takes to dismantle. End game roll PLUS random chance results in a much more consistent outcome over a period of time than simply relying on the RANDOM CHANCE of getting a good end game roll.