First of all, I am sorry for my curt reply. It came out much more impolite than what I was aiming for. I reread myself and was asking myself "Who hurt you, geez?".
I think I would have to agree with your description. You are absolutely right. Feelings need not be involved in a sexual encounter. However, that does not make it porn, per se. If the story has a need for that sexual encounter, then it is not porn. If the story revolved around sexual encounters without the characters getting any growth out of those encounters, then we've got porn.
You said it better than this, though.