I use a cascading RR where PCs resist using Will or Magic. Morale & Fear are seperate things. PCs can also develop Leadership & Public Speaking, roll it and the bonus achieved add to the Resistance of a comrad. Paladins & Clerics have spells that aid in the Resistance. These are all part of the mechanics of the game, and skills that a PC can easily develop. Whats the harm?
I believe that part of the mystique of fighting undead & demons is overcoming the fear to do it. Only a select few can stand against a foe that so blatantly defies nature & is in its very nature, evil. It can easily be what seperates the professional soldier, town gaurd, or mercenary from a hero.
GMing is very much a matter of style. I'm not the sort that throws PCs up against a few skeletons or zombies every other session. But, adding another layer to the challenge of fighting them makes players approach the situation differently in most cases.