Did you look at the OTHER trees? They have a lot of this stuff. And since healing amp is a unique feature of this game I don't see any reason why Barbarians shouldn't get more than ANYBODY--they need it because their self-healing comes from crappy pots and various special abilities with sharp limitations on them.
After viewing all 3 trees I have to say I think it looks pretty workable. It's not what I would do--and the damage increase seems pretty small--but the toughness increases look solid, at least.