Interesting argument you make about flexibility. I feel the same. We don't see players that feel confortable all around the pitch anymore. We used to have total attackers like Henry, Bergkamp, Ronaldo. Wich position they played: CF? Winger? False nine? Second striker? Yeah, all of them.
The modern football is too sectorized. That's an ugly side to Guardiola's positional play becoming the dominant footballing culture. Some players require more freedom than the system allows them.
That's the problem with brazilian football right now. Trying to tell young players that they either are a winger, a cf or a 10, and that they should therefore stick to one determined area of the pitch. But our culture is that the best players should be with or near the ball at all times, and sticking to your position waiting for the ball to come (as Guardiola did to Henry, for instance) is extremely unnatural. If Ronaldo was born in this generation, coaches would certainly make him a winger that sticks to the sideline at all times.