All right. Now that this trail has gone cold, let's pick it up again.
Gygax, as quoted already says in his explanation of The Monster as a Player Character that:
"You have advice as to why they [monsters] are not featured, why no details of monster character classes are given herein."
In the very next section, I shit you not, Gygax provides a page and a quarter (pp.22-23) with rules on how to manage a character that's been made a lycanthrope, how to run the character AS lycanthrope, rules against experience gained when acting as a lycanthrope, what conditions cause a player to turn into a lycanthrope on a given night of the month and suggestions on what should matter to a character's future behaviour if they are turned into, respectively, a werebear, wereboar, wererat, weretiger or werewolf.
Yep. Gygax — who either has a split personality, or who takes the credit for other things written by other people, or may just possibly be a hypocrite, as I've said earlier — on the page after writing a long diatribe as to why monster characters shouldn't be played, writes an even longer section on how to play this specific type of monster character.
I tried, when I was young, dumb and full of cum, to run these rules. They don't work. They don't make a good game. The player, sick of the sequence, removed the curse after three months of running the character once a week and it was never spoken of in our group again. In all the time since, I've been hesitant to run were-anythings. The 3rd level cure disease spell, and the presence of a paladin in the party, makes the "lycanthropy threat" as meaningful as a bad cold; and so, I don't treat it as a disease. The lycanthrope actually kills the victim; wastes all its hit points; then flees with the victim, to ensure the victim will turn into the lycanthrope: and then the victim is DEAD, period, even if it is killed again.
Thus, lycanthropy is as serious a form of death as any method of reproducing the undead. What makes death by the nastier of undead especially frightening? Permanency. Transformed by a shadow into a shadow, you can't be raised. When Lucy Westenra is transformed into a vampire, and is killed with a stake by her fiancee Arthur Holmwood, she doesn't transmogrify back into a human and they kiss. She is dead. Dead, dead, dead. If you think that you can always escape death as a player character by shelling out cash for resurrection, don't die by wight, vampire or werewolf.
If the character becomes any of these things, then NO, the character doesn't get to run the monster. This isn't Buffy the Vampire Slayer, you're not Oz, you're not Spike, you're not Angel. In this particular case, I am very old school.
When Lucy—I call the thing that was before us Lucy because it bore her shape — saw us she drew back with an angry snarl, such as a cat gives when taken unawares; then her eyes ranged over us. Lucy’s eyes in form and colour; but Lucy’s eyes unclean and full of hell-fire, instead of the pure, gentle orbs we knew. At that moment the remnant of my love passed into hate and loathing; had she then to be killed, I could have done it with savage delight. As she looked, her eyes blazed with unholy light, and the face became wreathed with a voluptuous smile. Oh, God, how it made me shudder to see it! With a careless motion, she flung to the ground, callous as a devil, the child that up to now she had clutched strenuously to her breast, growling over it as a dog growls over a bone. The child gave a sharp cry, and lay there moaning. There was a cold-bloodedness in the act which wrung a groan from Arthur; when she advanced to him with outstretched arms and a wanton smile he fell back and hid his face in his hands.
She still advanced, however, and with a languorous, voluptuous grace, said: —
"Come to me, Arthur. Leave these others and come to me. My arms are hungry for you. Come, and we can rest together. Come, my husband, come!"
There was something diabolically sweet in her tones — something of the tingling of glass when struck—which rang through the brains even of us who heard the words addressed to another. As for Arthur, he seemed under a spell; moving his hands from his face, he opened wide his arms. She was leaping for them, when Van Helsing sprang forward and held between them his little golden crucifix. She recoiled from it, and, with a suddenly distorted face, full of rage, dashed past him as if to enter the tomb.
As Seward, Morris and Holmwood realise, it is not Lucy at all — not any more. She is a monster. And this is what some monsters truly are ... if not evil, then certainly things so hideous that they cannot be tolerated and let free. They must be destroyed, even if they were things once loved by the destroyers.
These themes are utterly lost to the seminal gratifications of modern writers, pun intended. The trials of monster killing is not the childish syndrome of "ought we destroy the monsters?" ... but what do we lose of ourselves when we're forced to murder even the most hideous of things? What price do we pay in defending decency or rightness? What are we, once we've seen the worst the world has to offer? What have we left to hope for?
It is hard to bring a party around to experience this; most, naturally do not want to experience it. No one wants to be Seward, above, describing Lucy throwing the half-murdered child aside, before attempting to seduce her husband. But "want" has nothing to do with it. The underlying horrors of lycanthropy and other unnatural abominations are keys on the piano that the DM can play, if we dare investigate the sounds they make. And if players can be made to hear that awful music, upsetting as that would be, the payback is an adventure the players won't quickly shelve in their minds. We use the word "haunt" to describe memories that won't go away.
As a DM, I strive to leave those memories.
I can't do that by reducing lycanthropy to a bad case of warts.