How setContentScalefactor can be used for using Ipad Retina images in Ipad.

I have set content scale factor to 0.5 ,using screen to design size ratio. But then is it like I need to use setScale(factor) on every CCSprite I used in the game? I thought scaling will be done automatically based on the factor set in setContentScaleFactor.
Why scale factor is not set on a CCSprite while creating it ? or what are the complexities and complications for doing this ?
I added CCNode::setScale(0.5f); in “initWithTexture” and it works just fine , quickly I got to know how my IpadRetina resources would appear in Ipad . yes scale factor is hard coded as of now.

Please share your thoughts.