TTK Blues > TTK Legendaries

Okay this is messed up, why in the world is my brand new legendary gear capable of being replaced by a blue by as much as 10-15 attack/defense points. Like this is ridiculous, the only way the legionaries i get can actually be worth a damn is if i buy them from the vendor, any other legendary you get from a drop is scrap which can and will be replaced by a blue in the blink of an eye. this is fricken heart breaking, bungie can you please fix this?

TL;DR TTK Lengendaries = Garbage. TTK Blues = God Tier.