The Soulburn system of Cataclysm was a big bust for affliction, offering plenty of utility but lacking in role-buffing damage abilities. The biggest issue was that Soulburn didn't feel like a real resource. Soulburn largely felt like a complicated set of "oh, crap!" buttons.
In Mists of Pandaria, demonology and destruction are each departing from soul shards to gain new secondary resources. Soul shards will be affliction-only, so it's finally time to tailor shards to affliction purposes. Unfortunately, beta is where many things are broken or unfinished, including soul shards.