That's because they're meant to be magic orriented, contrast to the melee based werewolf.
There is a perk to add poison damage to their melee attacks, so that shouldn't be half bad.
It makes a lot of sense though, werewolf focuses on melee, and vampire lord focuses on magic. Kinda balanced, but you can become a vampire lord as often as you want (as far as I know at least), but as a werewolf you can transform twice at the max per day