Big things might, sure, but that's not necessarily what we were talking about here. Honestly, it really depends on what you're going for.
For a different perspective, a reasonable big thing catch might be +1: Radiation, and other penetrating effects where being bigger just exposes you to more of the effect. (This is +1 on the assumption that wizards - a reasonably large category of supernatural individuals - could probably pull of some sort of relevant evocation if they knew the catch. If you cut the catch down to just radiation, that'd probably be a +0.)
Or it might be +2 to +4: Any area effect attack - hunting mammoths with spears kinda sucks; hunting mammoths with grenades or maybe ballistae or by dropping really big rocks on their heads from a clifftop, on the other hand...
I could see deciding that were-creatures just have more "vitality" than other things and that the stuff-that-attacks-lifeforce catch isn't appropriate for them, though. However, once you're dealing with supernatural vitality, then, imo, you're probably also dealing with something with a more traditional supernatural catch - silver, or the like.
Depends what the GM is going for, really.