I am not saying they had no sensation of anything. Their experience was no less real. We may not feel that our feelings are real all the time, because we know there is something more real than what we are experiencing right now. But what they experienced in the garden, pure bliss and no lack of pleasure as God prescribed (according to His will, not the hedonistic or guilty pleasure of today), was then marred by their choice to sin when they were tempted.
Often we speak of pain as beneficial because we have sensation and a nervous system, etc.... but what I am pointing out is that pain can be seen as an extension of death, the result of sin.