The thing with WASD is that it leaves your little finger free to hold down Ctrl or Shift to do thing like crouch and run. It also leaves various other buttons like TAB, Q, E, F, R & X in easy reach for things like Use, Reload, Switch weapons, Flashlight etc. etc. and all while keeping your thumb resting on the spacebar.
I've known of some people that use "ESDF" (same as WASD moved over one space) to free up the Q,A,& Z keys for extra functions, but never heard of anyone using "ASDF" before. Frankly it sounds cumbersome and I imagine with that arrangement you'd have to keep switching positions if you want to do anything other than move jump and shoot...which I suppose to be fair is all some games involve...