It really depends. A lot of people do just dress fancy and have the headphones. If you look at the actual PV with Miku and Luka, they have specific outfits. As well as some of the other official versions like with Rin and Len. And even some of the Vocaloids have different kind of wings than butterfly, like Teto and Ted.
I do have to say Magnet is one of the over done and easy cosplays done. But there are ways someone can make it special and out there. I've seen couples actually make the version of them when they have actual butterfly wings on their backs. Also, working hard on the headphones and making them really nice, maybe even light up really helps the cosplay quality. But for the most part, most cosplays for this PV isn't thought out too much.
Personally, I like doing Magnet b/c the song really speaks to me and I do really enjoy making the headphones. The only thing that irritates me is all the people doing crossover stuff with Magnet...