The level adjustment makes sense to a degree, but I think that a non-classed 1 HD (or less) creature who contracted lycanthropy could replace the base creature hit dice with the lycanthrope animal hit dice, per Savage Species. This assumes acquiring lycanthrope animal hit dice is treated as picking up class levels.
So one might start off as a non-classed afflicted werewolf (2 HD, ECL 3) and pick up one level fighter (3 HD, ECL 4), or start off as a human fighter 1 (1 HD, ECL 1) and be afflicted with werewolf lycanthropy (becoming 3 HD, ECL 4). End result is practically the same. A commoner 1 OTOH is classed and would have 3 HD as a werewolf.
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