I have a few extra percent spellhit on my mage, and I think that because of it, my damage has gone up (a critical miss still nets 0 damage).
I also think that Hit/weapon skills make a bit of difference. If blizz didn't really want them to be utilized or their benefit fully realized, they wouldn't have put +24 Feral Abilities on Earthwarden (for those wondering, it reduces blocks/dodge/parry by just over 6%). On my druid, I've noticed that if I miss 2 specials in a row in the first 10 seconds of a fight, I can pretty much forget about holding agro. Adding a few percent +hit and +feral attack would all but eliminate all missed opportunities for additional threat. I've got my Def over the needed amount; at this point, i'm juggling extra armor/hp/AP around, without losing too much rage generation.
On a side note with that, Daire noticed that if she changed some of her gear to DPS gear (while not sacrificing her Armor, HP, DEF by changing gems and enchants) she was doing more damage, resulting in more rage, which results in more damage.....meaning lots more threat to go around. yay!