Stormonu
NeoGrognard
I'm mostly of the same thought; you should need silver to take them out, and magic weapons just buy you some time. I do think that non-magical BPS resistance/immunity is far to common in base 5E, but I think they went too far the other direction. For example, I think you should be boned if you face a gargoyle without a magic weapon (and they should be resistant to earth/air magic on top of that), some fey should have vulnerability to cold iron - but I wouldn't give them any kind of resistance requiring magic weapons.Getting back to the OP, I think lycanthropes should be specifically resistant to damage from anything but silvered weapons, and you should need a silvered weapon (or maybe the magical equivalent) to finish them off, just like you need fire or acid for a troll. It's such a part of the iconic lore that it feels weird that they are now just another mundane creature, for the most part.
I also hate that most creatures have lost their immunity to non-magical weapons; I would have gone the other way: keep the immunity to non-magical, and buff it to include resistance to magical.
Too many times I think it was used as a crutch to keep hp bloat down on higher CR monsters. The better answer is just don't give the PCs so much firepower in the first place.