I don't think it's useful to draw comparisons between Brady's dink-and-dunk style in his first year in the league vs. Cassel's. Brady's offense ran that way because they didn't have the types of receivers Cassel has today. Going from dink-and-dink to airing it out isn't some established blueprint for the evolution of an NFL quarterback; one type vs. the other is largely based on the types of receivers you have, the coverage schemes of the defense, and the overall arm strength of the QB.
I don't buy the idea of sticking to a dink-and-dunk offense simply because you don't have faith in Cassel's ability to throw the ball downfield. You have to play to the strengths of your receivers, and this offense is designed to be opened up... if they are going to effectively castrate Moss and the rest of the receivers because Cassel doesn't have the ability to utilize them, then I have no idea why he would be leading this offense right now.