The rest of the tree will make the beast tougher and more voracious, and eventualy able to summon other werewolves. It's an intensely physical play style that I and a good many others over in the call of the wolf pack part of the forum thuroughly enjoy.
An extra 100 points of Health and doubling healing from feeding won't really make Werewolves all that much tougher. On Adept, a Ancient Dragon can hit for 300 damage, and does 600 damage on Master. A Draugr Death Overlord with a Ebony Bow can one shot basically any Werewolf. With 0 Armor Rating, a Werewolf gets torn apart by anything that can do high damage. Having a higher health pool, just means that you have to feed that much more often. If the Werewolf is up against something that he can't ragdoll, or is up against multiple opponents at once, he's in some serious [censored].