Sex is a physically intimate act that involves one or more persons (masturbators and orgy fans welcome!). Sexuality is a vague concept that encompasses all sorts of things, including but not limited to the sex act itself. You can be sexual while not having sex. Indeed, sexuality can be a large part of your life even if sex is a relatively small part. It would be wrong to assume that somebody who embraces sexuality is a person who has lots of sex, or worse yet, a person who has indiscriminate sex with lots of partners - don't succumb to this stereotype. Surely it happens, but don't assume that if somebody likes sex, they are therefore a "slut". That's a product of sex negative thinking.
I like to trade the term "sexuality" for "sensuality", which suggests a softer approach. I am an erotic artist, and sensuality is a huge part of my life. But I am not constantly having sex. Sensuality, to me, is having the constant knowledge in the back of my mind that I am a sensual, sexual creature. That I am constantly on the lookout for - not sex, necessarily, but - erotic triggers. Laying eyes on an attractive person itself is usually not defined as sex, but it is absolutely a part of the overall realm of sexuality, and for the sensualist, can be fulfilling in and of itself, even without leading to anything further. Being aware of these triggers, and being open to receiving them without requiring certain outcomes for satisfaction, can help you to live a pleasurable, stimulating existence. This may not be sex, but it is sexual, it is sensual, and in my life, it is what I refer to as art.
"It is not the artistic aptitudes that are secondary sexual characters as some shams and shamans have said; it is the other way around: sex is but the ancilla of art."
- Vladimir Nabokov (in character)
Art can be many things, including things I'm not about to describe. But for me, art is the pursuit of beauty. Beauty, too, can be many things, and is a subjective quality. But for me, the ultimate in beauty is erotic beauty - sensual beauty. For me, art is the realization of perfect beauty, an existence between reality (the source and subject of the art - more apparent in photographic than in other art forms) and fantasy (the conceptual inspiration as well as the audience's emotional and cognitive reaction). Thus, it is not that erotic art is a form of art capitalizing on the popularity of sex, but that sex itself is a crude approximation of the "perfect form" of pleasure, of which art, like some kind of magic, can approach even closer.
I do not expect everyone to agree with this approach. Naturally, there are those who will never be convinced that art can be more satisfying than sex. And that's fine. Let the sexualists enjoy their sex, and the sensualists enjoy their art. To each his own approach. But if you feel I have hit on something important here, you may want to explore a little deeper my thoughts and views on sensuality.