There are many reasons to have memory items..
Actually there is only one reason to have memory items, they are tasks which must be actioned without delay in circumstances that do not allow time for a checklist to be consulted. They should be strictly limited to the "do or die" items such as initial actions for stopping, engine failure, decompression and unreliable airspeed, can't think of anything else that needs them really, evacuation should certainly not be performed from memory, plenty of time to set the park brake and get the QRH out.