Her 'persona' as presented by her record company
Her 'persona' as presented by her record company is different from that when she first premiered as an artist. All promotional materials with her seem to showcase her as some 'dark' type of artist - almost an antithesis of her original appearance. It seems as the A&R's/Agents/Record company completely went and committed with the tagline 'good girl gone bad' (I thought it was only for that one album, but nope).
First blame goes to the record company, Def Jam - a once historic and influential hip-hop label, now in the business of pop R&B all in the space of 4-6 years: in the early 2000's their distribution of albums by DMX, Jay-Z, and many others contributed to a certain status...and now we have Rihanna and Kanye's emo-hip-hop (great).
Second, Rihanna herself: in order to succeed in the biz she sold herself and her image out big-time. Ever since she got that ugly ass bob haircut that showcases her big forehead she exudes something like she thinks she is the best - not humble at all, considering her voice talent is limited at best.
Lastly, Radio: the stations must've got a big paycheck to continuously play her songs ad nauseam..so much so that eventually a person gets used to them, and then sick and tired of the rotation.