Well for sieges and mass pvp WL is hands down a lot more useful than a destro, great stuns, cooldown length increasing skills, interrupts etc. What comes to dealing damage, yea WL cant burst as much as destro can but remember that WL > Destro in oly and 1v1 so he isn't totally helpless.. Destros dont do shit in pvp since theyre slow and will get even more slowed and kited if enemies are even half-assed.. All theyre good is whacking raidbosses and nowadays their PvE is nerfed too (frenzy going off when gaining too much health).