Totem of Wrath is typically for longer fights not needing as much movement.. which means it's better for PvE. Nature's Swiftness is perfect for throwing down 2x chain lightnings in about 3 seconds. I'd rather have double the damage and chance for crits in 3 seconds than one cast at +12/15% hit/damage when it comes to PvP.

However, Totem of Wrath isn't totally useless in world PvP.. it's just not as good as an instant cast chain lightning. I'll mainly use magma totems in standard PvE fights, and break out totem of wrath for instances or extended fights against stronger bosses (like the Overlord quest in Hellfire Peninsula). Fire nova totems seem to work better in world PvP over wrath, since enemies typically will try to run circles around you, and magma is too much low-power steady damage.