List Break - Diva/Rap Songs

So, people told me that one great song I left out of the decades list. The song was Umbrella by Rihanna and Jay Z. I remember that it was a big hit, I remember being impressed by the video, but I forgot the song. It was a pretty good song, but there was one thing that I didn't get. Why is Jay Z in it? I love Jay Z but his placement seemed to be a bit random. He's just rapping like normal and then the song just goes into a Rihanna song completely out of nowhere. It was like the song decided that it didn't want Jay Z so the mic just ditched him in the recording studio. Why are there so many songs like this? There's always the song that becomes a huge hit that has some famous rapper with a popular female singer. It's a good idea but the two just don't go together very well. Besides this trend of rapper/diva songs also launched the way overdone Whitney Houston/Bobby Brown relationship. I think that by the time she divorced him we were sick of hearing about it already. Just thought I'd mention that.