What is the purpose of transforming into a werewolf? They die waaaaay too easy, but it is called "beast-form", does light armor make them more durable? Or is it for lower difficulties to have "fun"?
Its for lower-level fun. During the first ten or fifthteen levels of the game the beast form can clear ruins with ease. Even silverhand ruins. Given that no skills are used with beastform one could stay at low level for sometime. I did the entire companion questline at level 10 using beastform in each ruin. (the rine of hicrine helps). The thing to remember about the werewolf is its fast you can often dodge around an enemies attacks and deliver massive power attacks to send foes flying.
If you really want long term werewolf fun you need to invest in alteration and alchemy. Using a potion of alteration to prolong a dragonskin spell soo it lasts an entire dungeon for 80% Damage reduction.
They have special shouts that make them very useful, especially the first one you start with (fear). I agree that they are pretty weak when it comes to the damage they can take and put out.
Compared to a legendary enchanted weapon with lots of fortify weapon skill yes. But by level forty it 80dmg a swing and they regenerate stanima so quickly you can power attack constantly. They're also damn quick letting you dodge swings. The real weakness is defensively.