A Discussion of the newly dropped Thori'dal bought up a lively discussion on Legendary weapons in my guild chat the other day, which has in turn set my own mental wheels turning. Looking at the difference between the pre-Burning Crusade Legendaries and the Burning Crusade Legendaries, there's one big difference that stands out (beyond the level difference): The pre-BC Legendaries were quested, while the BC Legendaries have been drops.
The clear-cut off seems to suggest that at some point, Blizzard decided that creating long, involved quests in order to obtain Legendary weapons just wasn't the way to go, and they'd rather let the RNG take care of distributing Legendaries. But the question is, did they make the right choice? There's good arguments for both sides.