Okay, so what's the deal, anyway? Why would someone get fifteen piercings in his face?
One approach to answering that question begins with discussing an aesthetic that's somewhat more abstract: music.
Bear with me here. This may seem like it's off the topic, but it's really not, I promise.
I listen to industrial music. Industrial as a genre is far from the most popular style of music; most people, upon first hearing industrial music, are apt to complain that it doesn't sound like music at all.
Music is completely a learned appreciation; learning a style of music is somewhat akin to learning a language. Any style of music is apt to sound like noise until you become familiar with it. When you learn the structure and form of a particular style of music, you learn to hear the melody and the harmony, you learn to separate the components of the music, and you learn to appreciate it. Even the conventional eight-octave scale is learned, not a fundamental part of nature; music exists which does not use the traditional scale at all.
Some forms of music are easier to learn than others. Industrial music in particular is quite challening. Good industrial music is arguably some of the most complex music being recorded today. It's often densely layered; it may use sounds that are unfamiliar in the context of music; it often does not bear a structure which in any way resembles any variation on the "verse/chorus, verse/chorus, verse/bridge/chorus" construction of most popular music; it may change key, rythm, or time frequently within a single piece; it may contain dissonance, or contain more than one melodic line (and those lines may differ in key or even in time signature themselves!); it may establish a pattern, then break that pattern in unexpected ways; it may contain vocals which are distorted, pitch-shifted, or otherwise manipulated in untraditional ways.
In short, not only is it unfamiliar, but it's also so complex that learning the aesthetic of industrial music is much more difficult than learning the aesthetic of many other forms of music.
For me, this complexity and dense structure is the biggest appeal. I can listen to a good piece of industrial music six times in a row and hear something new and different in it every time.
But that complexity also serves to make it inaccessible. Learning to appreciate industrial music requires work. Listening to industrial music requires active attention. If you've never heard it before, then it sounds, yes, freaky and scary.
In many ways, body modification--and by that I mean not just body piercing and tattooing, but also scarification, branding, bifrucation, and other forms of body art--is very similar to industrial music. Like any aesthetic, the aesthetic of body modification is learned; but like industrial music, the aesthetic of body modification is not easy to grasp. It requires work, and at first exposure, it can seem quite inaccessible.
There is a qualitative difference between, say, a heavily tattooed sailer of 1942, and a heavily tattooed college student today. Often, that sailor's body may be a patchwork of unrelated tattoos, each by a different artist and with a different subject, each acquired in a different port. A person today may have just as much ink on his body, but the odds are better that the entire tattoo was designed and conceived as a whole, and executed by a single artist. At first glance, you may see nothing more than a freak with a shocking amount of ink covering his entire body; it requires closer examination to realize that all that ink is part of a meticulous, carefully-crafted design that expresses a single vision. Seen up close, these tattoos are masterworks of complex and intricate detail, and they can be breathtakingly beautiful.
The person wearing such a tattoo is not seeing to shock anyone and is not out for attention; more likely, that tattoo is a highly personal work of art, executed for highly personal reasons.
The same is also true of piercing and other forms of body modification. At first glance, they seem weird-looking; and indeed, by the conventions of twentieth-century middle America, they are. But the only real difference between someone who wears a lot of jewelry and someone who wears a lot of body jewelry is the manner in which the jewelry is attached. Jewelry is both ornamentation and personal expression; nobody finds it unusual if someone has a ring or a necklace that has personal, sentimental value, and for body jewelry, it's really no different.
Any aesthetic is learned. Personally, I think the ugly, oversized, faux-American-Indian turquoise bracelets and rings that were so popular among women over a certain age a few years back is far sillier, and far less appealing, than body piercing is. At least those who practice body piercing have the courage of thier convictions... :)
I'm sure there are those who understand industrial music and don't like it, just as there are those who understand the aesthetic of body modification and don't like it. But there's a vast difference between those people and those who call someone a "freak" because of his chosen style of ornamentation. When you call someone a "freak," you are not reacting to an aesthetic; you are simply reacting to the unfamiliar.