Of course, movies make it seem like it is easy and sexy-every shower sex scene is always passionate and incomplete haste but that is not the reality. Shower sex in real life is not that glamorous-it is kind of unhygienic and has a higher risk of getting into an accident if not done carefully. So, it is rather a matter of making the whole aura sexy and dirty than the visuals of it all. Male bodies are often predictable-the cocks, if not possessing rare magnitude or look, appear just similar to each other. In gay porn, what is emphasized is the feeling of tension and building up the lust between the two. It is about showcasing the voyeurism involved in female anatomy rather than the actual sex between the man and the woman.
It is not the same as when it is done by heterosexual couples, because in straight porn it is usually about flaunting the bodies of the women. One of gay-popular aesthetics is shower sex.