well the reason I said it's not a big difference is what Sarcatica said.

Specifically, at lower levels, your health pool is so low, what 10% dmg you reduced won't reflect very well there from a healer PoV.
At higher levels, in most dungeon settings you end up pulling 2-3 packs of mobs anyway. being able to rotate ROH on 3 of them hardly makes a difference given the grand scheme of things. (you can pick which ones you want your str down on, to make a bigger impact however, it is good practice)