When shamans were released Shocks were grossly over powered, Earth Shock - no cd, interrupt and Frost Shock - no cd, slow. It was a pvp change to make shocks on the same cd and now its just part of the class design, making it one of the remaining elements that make a class unique. Considering Shamans dont have any "class resource" its balance behind that now. I know class design is a foreign concept these days, its still important even if every one wants every class to be the same.