Very lame to see Bono doing this, but what's even lamer is Diddy using the melody of Black Sabbaths "Iron Man" in this song.
First, it's not Diddy's song. It's a Kanye West track. Second, hip hop has a LOOONG and vibrant tradition of sampling music to make something new. So unless you're going to dismiss an entire genre of music...
What's vibrant about lacking the musical capacities to write your own original musical accompaniment rather than just lazily stealing other people's work?
If Green Day can write their own music, then surely anyone should be able to.
I've also heard some truly brilliant hip hop artists that largely write their own musical accompaniment. K-Os, for example.
Are you familiar with postmodernism in terms of art, with its conscious recycling of older ideas? Hip hop is a postmodernist musical form. Moreover, there's been a long tradition in blues, folk, and country music of passing melodies and lyrics down. If you're going to pick on hip hop for reusing the same melodies, you'd best go after blues, country, folk, and early rock music as well.