How Come Nicki Minaj's Starships isn't hip-hop?

So I was thinking about this after the whole Hot 97 thing. Why is it that Nicki Minaj feels the heat for doing so much pop and crossover music from some members of the hip-hop community? This little concept further intensified while I was watching some video from the musical duo 'Karmin' who crossed over for doing covers and especially for their rendition of Chris Brown's "Look at Me Now" and the