Problem Solution: If a character gets infected...how exactily is he going to learn this skill when he doesn't even know he changes? IIRC most were-beasts blackout when they change during the full moon unless they're a true lycanthrope.
This is actually addressed in the MM - it's a Wisdom check (DC 15) to
figure out what happened.
Something to key in on, however, is that the first time you voluntarily
change, you immediately and permanently assume the alignment of the
applicable werebeast -- and in RL, that generally means Evil.
It becomes really interesting. A PC needs to build up ranks in the
Control Shape skill to resist an involuntary change -- but using that
same skill, a *much* easier task is to change voluntarily. Virtuous PCs,
building up that skill to muzzle the curse, will have a powerful ability
just sitting