I like Willie Parker. If anything this boosts my respect for him. He's humble, and respects what Bettis and Staley used to be.
Still, Parker is the future for the Steelers. Just because he's humble and a good person doesn't mean anything except good things for his value to the steelers as a teammate, and ultimately, the respect he'll get from cower, which will translate to PT. He never said he couldn't carry the load, in fact, he sees himself as capable of handling 20 carries a game.
By the way, Parker doesn't make lineup decisions. If he's clearly outplaying the injury prone bettis and staley, why wouldn't he get the ball?