They're not staples... they surgical steel captive bead rings (the ones you're mistaking for staples don't have the beads in place yet)... the piercing is called a "corset piercing" and is not intended to be permanent - a series of surface piercings are made, jewelery inserted, then ribbon or sometimes chain, etc are woven through the rings to create the illusion of a laced corset... often this is done as part of a performance, for a photoshoot, or an event... and as to the 'why?' part of it all... just because really... for me the piercing is a high - major endorphins are released creating a sort of fuzzy euphoric feeling... ritual piercing has gone on in various cultures around the globe for ages and ages...
Hope that clears things up a bit for you...
I wish the images from the body art were of better quality... Meaghan is gorgeous... and apparently the kind of girl I'd be friends with... :0)