Jesus's penalty for "sin" had to include physical and emotional pain - in order to make it more meaningful for us.  We know what physical and emotional pain is and when we see the suffering of the Lord we are better able to understand what He went through for our sins. 

Jesus' emotional pains were due to our weaknesses ... each time we turn away from Him and refuse to acknowledge His presence, we are adding a load on His back ... our rejection of Him ... the times we despise Him through our callousness - cause Him deep grief and the sins we commit weighs Him down.

The physical pains He endured - the crown of thorns, the whipping with mettle thorns, the ridicule, the deriding, the pushing and the pulling - the wounds He endured for our sins - were to make us whole and be healed -

Jesus carried the burden of our iniquities and suffered the physical and emotional pains for our redemption.