Yes, it is a form of expression.
Sexual excitation is an emotion, creating something designed to illicit that emotion is a form of expression.
Just as you write a book or make a movie or paint a piece of art to try and illicit emotional responses... the exact same thing is done using porn.
Arousal is an emotion. It's no different than hate, fear, excitement, intrigue, wonder, bewilderment, confusion, love, lust, disgust, etc, etc, etc.
Emotional expression is expression... again, not necessarily the highest form of expression, but... no, no I think, in humans... it actually might be ~the~ highest form of expression.
It's like the old adage, "sex sells"... it's the reason why sexualized content is used prolifically in advertisements... because sexualization ~is~ the highest form of expression in humans. Because humans are sexual beings, much of our inherent, baseline nature is deeply rooted in sexualization in such a way that nothing, literally NOTHING attracts our attention more than sex.
So no, you are completely and totally wrong to the point of actually being in direct contradiction to your own human nature.
...maybe you've got a medical problem dude. Do your balls not work? You should probably go see a doctor.