And regarding to swtor. bosses in the flashpoints at least do have drops, but have tokens, pretty much like badges to buy items you could use in case the boss doesn't have/ drop your item. In regards to end level, based on what i saw on vendors, it is actually possible to not get a single drop from a boss because the vendors have items for every single slot.
About the 4piece set bonuses for tanks in T13. You kepts mentioning madness of deathwing. But looking at the heroic mode Dungeon Journal descriptions i'm almost pretty sure they're more intended for Ultraxion. I'm almost certain its going to be mandatory to have at least one of the tanks with the 4set bonus. Or at least mandatory for the non-top 100 guilds or somesuch.