To be fair the entire community didn't catch Spirit claws until a week or two in, and there's millions of us.

The community does not have the cards on hand to playtest like the developers. Also, a significant portion of the community simply is not very good at the game.

Spirit Claws is pretty close to Light's Justice or N'Zoth's First Mate in terms of functionality and can be used as references in terms of power level. A "ping" in a non-ping class like Shaman will always be good. Consider how much play Maelstrom Portal sees versus Twilight Flamecaller or Arcane Explosion.

Also, Spirit Claws actually wasn't initially very popular in Aggro Shaman. Only the resurged Aggro Shaman runs it. For a while, it was only present in Midrange. Finally, you assume Blizzard has an issue with Aggro Shaman at all. Blizzard as a whole is more friendly toward aggro than the community.

When Aggro disappears like during the Karazhan Midrange Shaman appears, deck diversity suffers significantly. It turns out that some tier 1 midrange decks are great at handling both control and aggro.