A very finely constructed argument, which would hold water were it not for a few things...
"i cast magic missile and he takes 17."
"I throw lightning bolt, save for half."
"i cast hold monster. Save or..."
"I hit him with melf's Ice Arrow, which i had memoried thinking we would see salamanders."
etc etc
In the werewolf legends you want to recreate, the werewolf was also not brought down by low level mage spells which were able to bypass his tremendous invulnerability like knifes thru butter either.
DND is VERy clear that magic does absolutely bypass DR, time after time after time after time, whether low level magic like magic missiles against really high Dr or not. It just goes right thru.
Unless of course its magic on a magic weapon. Magic on a magic weapon is inferior to say "silver or iron". technically tho, i would guess if the magic on a magic weapon is magic like fire or cold, then it goes right thru, ignoring DR.
Snow Elf Warrior: "My blade is made of enchanted ice taken from the lair of the dragon of winter. But hand me that dinked up silver plated shortsword, cuz these werewolfs are tough."
Mage Companion: "Don't worry. i got Freezing Hands prepared and it will cut the werewolf down quick enough. if nothing else, i got magic missile to fall back on."
Cleric companion: "And if that doesn't do it, i got my spiritual hammer, which being a force effect..."
Old gypsy Woman in the corner shakes head "Somet'ing t'lls me I 'm in wrong legend!" aSpits and walks out.
"all you need is a hammer"??? yup, one called "magic missile"
Mercule said:
And this is the #1 reason why I love it.
Think of legends. The legends don't say "werewolves can be harmed only by silver... or magic." They just say "silver." Ditto for fae and iron.
Imagine the great lycanthrope hunter of legend, Fritz. When he's first starting out, he carries a silvered long sword. As he grows more powerful, he decides he needs an enchanted blade and commissions one.
The next time Fritz is called upon by a burgomeister to rid the area of werewolves, he says, "This talisman was specially forged to cut through werewolves," as he draws his sleek new cold iron sword ('cause he likes black).
Does Fritz look cool? Does he look like a legendary hunter of lycanthropes? Does he look heroic? No. He looks like the moron who brought a knife to a gun fight.
Even if you throw away the legends of silver and what-not, all you really are doing is saying that if you bring a LAW rocket into play, it trumps any mystic symbolism. Forget the screwdriver -- all you need is a hammer. Bigger and stronger is always better than intelligence and planning. Just more 'kewl toyz' with which to play and more 'power-ups' to gather.