Why Rihanna is always naked or half naked in her music videos ?

Sex sells?...that was easy. Hot girls/guys have been used to sell crappy, uninspiring music for a long long long time....
i think that she just needs some help i think that she is still dealing with the whole chris brown and Rhianna thing that happened 2 years ago.
That's how her record label dresses her, to match the sexual feel of her music.
Because She May Be Bad, But She's Perfectly Good At It !