Why is rap stupid as far as music goes?

The lyrics are absolutely terrible they are completely childish, immature and pathetic, the vocals (I don't cl it as singing) nearly all sound the same and they have that completely annoying tune behind the vocals that just repeats itself for the duration of the song, also I hate the fact that loads of people like it because it's in the charts and sells well just because it's popular doesn't make it good i.e. justin bieber