defense also increases chance youll be MISSED. very vital.
think of it like this; defense is a pure tanking stat. it does all of that above mentioned stuff and more (more defense also means a higher effective character level when it comes to being dazed, meaning a mob is very very unlikely to daze a warrior in tank gear). resilience does three things; it reduces periodic damage (which is nice). it reduces chance to be crit (like 1/6 of what defense does). it also reduces damage taken when crit.
while tanking, 1 of those never comes up, 1 always comes up, and 1 might come up sometimes. if youre crit immune to a mob, then the crit damage reduction is essentially useless. the periodic damage reduction, while nice, really isnt worth a much higher chance to parry, dodge, block, be missed, and avoid daze.
in sum, using resilience as "tanking" gear is nice for A.) patch jobs, when youve got nothing better, and B.) off-tanks who might still need to do dps, as resilience-heavy gear for warriors is also very dps focused.
Edited, Feb 2nd 2008 5:12am by Quor