It’s damage buff is multiplicative (I never noticed that before).
If you were to put all 8 points in that, it’s 1.08% X. Is that something anyone cares about? It’s a tier 8 passive and I always thought it was trash, but that is because I didn’t notice that it was mutli. I’m not convinced it isn’t actually still trash.
Of course , any more damage multiplier, especially when it comes from passives is worth it.
A conditional modifier like this obviously is onyl interesting if you can utilize it enough. So if you are a caster build or only a hybrid melee/caster build it might be not worth it. But as long as a significant portion of your damage is melee its hard to compete with % more damage comapred to other passives.
Generally most stats have a lot of diminishing return. And with independent more multpliers like this it is completely circumvented.
So yes, you should care about. Many people care about it 
So 8% more melee damage is good for any melee build but the problem is Shaman isn’t really good for melee (especially compared to Beastmaster) so its a mostly unused node.
I had a plan for DW Undisputed Gathering Storm Shaman but ditched it since Beastmaster was wayyyy better.
Then there is totem uptime. Not a fan of totems granting buffs unless they are retained sometime after they expire or are destroyed.