I don't doubt that there is a lot of simple music out there [I also don't think it's a bad thing], but I really don't think this song qualifies. Honestly this song musically is was more complex than a lot of the rock classics that nobody ever complains about. How many AC/DC or Aerosmith songs are really complex musically? This song has a great beat, this and Rude Boy have a sound that I don't hear much in pop.
A LOT of talented people are behind blockbuster pop songs. Michael Jackson worked with guys like Quincy Jones and Teddy Riley, and Rihanna works with some of today's best producers and songwriters.
I do agree with you that singers auto-tuning their voices has taken a great element out of pop music. Too many singers sound the same now, no imperfections, and unique voices are hard to come by. That said Rihanna's one of the singers that make it work. Her voice stands out from other singers.