You know they are just a good example of how the programmers choose that the player is in control and not the computer. I read the handbook and one of the programmers said " We dont force the player to do what they want,we just give them an option" and this is one of the best aspects of the game.
You can shoose whether to play DD the easy way or the hard way.
I played a rogue using death scorpions and i would find it a bit difficult without them,not impossible but difficult.
(Thats what i am going to do next time,try and survive without them).