If I were able to go back in time and talk to the 4th edition designers, I would advise them to make the "Essentials" player's handbook the Core Rules for players. Then, I would strip the powers of the Core Rulebooks (and other non-essentials rulebooks) and add them back in as equipment-based powers.
That way, for example, a fighter would be focused on making basic attacks while using his stances, but then could find, say, a magic shield that allows him to do the CRB power "Tide of Iron". So, there's no inherent fighter "Daily Powers" that "his muscles forget how to do"; it's his spear and magic helmet that allows him to do that awesome move once per day.
As I understand it, one of the ways that fighters in the elder editions of D&D were unique is in what equipment they possessed, so this would have added a sort of "retro" feel to 4e, while at the same time introducing what are IN MY OPINION, a better set of rules.
I would also ask them to make rituals less expensive; perhaps 10gp per level (of the ritual).
