It made sense for Fallen Heroes to be level 57-60 elite mobs when WPL and EPL were high-level zones and when Blood of Heroes was a reagent for level 60 stuff, but as of the Cataclysm world revamp WPL is now a level 35-40 zone and Fallen Heroes are still 57-60 elite which makes no sense.
There is no longer anything in the game that uses Blood of Heroes. Pretty much the only purpose they serve now is for griefers to troll levelers by looting a Blood of Heroes near a quest area.