I personally like piercings, because a) I get a rush from the burning pain of getting the actual piercing and b) it's a fun way to explore like subcultures, personal branding etc. Also, I think it's portrayed as a 'rite of passage' for young girls to get their ears pierced: I know it was a big getting-into-high-school thing for me.
I do agree that it's one of our weirder societal fashion practices, but then most fashion practices are: what the original poster said about the weirdness of piercings as a desirable thing could be applied to anything: "Lipstick! Icky tasting red paint you smear around one of your orfices! Weird!" "Body hair waxing: agonisingly painful, completely unnatural and infantilising, and hella pointless because it's just going to grow back into stubble in a week!"
You know, if you're going to have this 'what the fuck!?!?' attitude to cultural practices, then it may was well be applied to EVERYTHING in our culture.
Which would be a valied and good thing really: appearances and behaviour reveal and promote values and beliefs. It's v. intersting. Humans have had urges to alter their appearance/decorate as a form of distinction, status, and/or self expression for thousands of years. Like supposedly the earliest cavepeople 'fashions' (so to speak) that they've found were less about practical function and more about differentiating oneself aesthetically.
To conclude: piercings are weird. But when you think about it, most things people do are!