Well by that "anti-poser" logic Boxsters should not have 18" Carrera five spoke or Turbo twist wheels either...Anyone not rolling around on 16" or 17" wheels is a poser.
From the doors forward both the 97-04 Boxster and the 99-01 Carrera are the same block of sculpting marble. If anything the '93 Boxster begat the 1999 996, as its the only 911 that doesn't "fit in" when you look at the Carrera lineage.
I've yet to hear a Porsche purist accuse a 99-01 C2/S C4/S owner with a GT3 front bumper of being a poser....It's a matter of style. It would be pretty foolish to say "I'm adding a Turbo taco wing because I want people to think my C4S is a Turbo" People read the rear badge and know what the car is and that the owner has chosen to add some individuality to his car.
The 996 community is chock full of owners adding all manner of exterior bits that were not initially part of the factory look of their respective Carrera. I don't see how the Boxster would be held to a higher standard since its the car that started the whole design theme.