If Bony is this good, why don't Chelsea sell this useless heap of footballer Lukaku and buy the ready made version?
Well they are trying to do the "selling Lukaku" part. Probably because his inability to control, hold up the ball, and pass to a team mate isn't very good.
In the words of Mourinho about his strikers:-
"Our strikers are good strikers, but they are players with some specific qualities," Mourinho said.
"They are not the kind of players who in five square metres - with three or four players around - can get the ball, dribble on, see the space and shoot.
"So when the team is in a difficult situation they are not able to, normally, resolve the situation for us."
He could very well be describing Lukaku there, when marked tightly or against a deep set defence like he was the other night, like he was against Crytsal Palace - he is unable to do what he wants.