I prefer being able to rerun until I get the item I wanted over Blizzard's loot system of deciding for you if the boss will give you any loot this week...and then deciding which piece of loot you get, if any...and then deciding whether or not it's going to roll enough of an increase in item level to be an upgrade for you or not.

RNG may make you take a few tries to get your item (and I remember having to run A9 12 times in one week to get a bolt), but at least if you're persistent you'll get what you wanted.