I agree with most of what u said apart from this...
They key change between the kelly, tasker, hull, smith, etc years is Free Agency and the added complication of salary cap management.
It is so much harder to draft a guy and keep him for many years without breaking the bank - doing so with a high number of draft picks thsat routinely are at the top of their game is nigh on impossible.
Look at superbowl winners in the FA/Salary Cap era... No one team had a 'complete' team with a plethora of high performing, long-standing veterans like you describe... So much of the NFL today is based on breakout players who fade the next year. Even the Patriots have had holes each time they went to the show - but they are, as we all know, a special case.
I don't have a gripe about the ability to draft and retain the best players and retain them year in year out at their highest performance. What I would complain about is the ability of the coaches to harness the ups and downs of the players they are presented with... After all - after last year, on paper anyway, we were going to win the whole lot this season.