Matt,
Using JN and PD as your examples reminds me that taking on the responsibility of providing for your family and expecting them to extend the business affects things, much as it probably did for RTJ, Maxwell, Bell and several others. That noble goal is contrary in most ways to the idea of always being a fresh artiste, but that is also real life. For example, I believe (granting its none of my damn business) that the JN legacy would have been better served by doing a few select courses, rather than creating three of four levels of JN design from signature, to sibings to associates, to other tour pros, etc.
Lastly, while we all do similar things over time, I will again debate whether its all about the ease of it, even if some is. Most of us wouldn't turn down a job, believing we could do something better than the next guy, even if doing an average design and not a masterpiece. With that mindset, why turn down a job that is offered?
For the record I have no children interested in the least in becoming gca's....of course, my "gravy train" is really a local switcher vs. a speeding intermodal freight.....)
Your Hollywood analogy also brings up the question of comfort zones, which I believe we all stay in far too much, gca's included. Is an analoby that if your favorite football team finally makes the playoffs by being a dull, defensive oriented team that runs on offense and tries to open it up once in the playoffs, is that the best route to success, or should they continue to do what they do best?