You are right, he doesn't have to leave that team. But like I said, I would like to see if he is able to reach the same stats in a team like Bayern, Chelsea or AC Milan. They arent an "oiled machine" like Barça is. I think every piece of the puzzle landed in the right place for Messi: At a young age noticed by Barça, getting into this insane academy, Barça paying his full growing hormone treatment ... What would have happened when he didnt got noticed? I think he'll probably would have made the same journey as CR7.
He doesn't show off like Ronaldo does, that's true. That's what makes him a great sportsman. But come on, everybody loves a little piece of arrogance or a trick now and then :D . Everybody wants to be entertained !