Greetings!
Great stuff Volaran! I think you are understanding the dynamics in the right way, indeed.
I have been playing D&D since 1978 and running my current campaign world for essentially over 15 years now. I have always had the pleasure of having highly intelligent, ambitious, aggressive, and highly creative and innovative long-term players. For example, my friend Mark. Mark is the kind of guy who is famous for two key things: One, is that he is always tinkering with ways that the magic system in the game can be used and exploited to the maximum. He is literally a nightmare wizard player! A fun nightmare wizard player, but a nightmare wizard player nonetheless! Two, is he is always seeking to maximize not only the magical resources at his disposal, but also the mundane resources to the maximum as well. Then, my group of gung-ho, hard-charg'in Marines! Can you imagine what it is like DMing for a group of six, or eight, or ten U.S. Marines? They tactically optimize every resource and every person in the squad to be the most efficient killing machine that mowes through virtually any enemies that you throw at them. They cooperate instinctually, lay their lives on the line, and hammer their way to victory through superior tactics, committment, overwhelming firepower, superior resource management, and ruthless focus on achieving victory.
Then, I have a range of friends that have influenced my thinking, including my wife, as she is very good with resource management, playing wizards and druids, and in creating effective alliances and family dynasties.
For example, the premise in the game books is that a four-person party is assumed to do all of these great things. Hmmph!

I have players, and I play as well, as a hard charging, resource maximizing, creative, aggressive player. In my friend Dragonblade's campaign, I play four player characters; a male human 15th level wizard; a male human Barbarian 10/Fighter 5; a male high elf fighter 15; a male human fighter 10/paladin 5.
Each of these player characters of mine have approximately 16 cohorts, a cadre of leader and support followers, and 75-100 well-equipped troops under their command.
Now, as you can imagine, if you design the adventure for four 15th level characters, you are going to be hammered, because I am maximizing my characters abilities to the fullest extent--magically, socially, financially, and so on. I have characters in my own campaign that *in a single generation* created a caravan company that specializes in wagons enchanted with refrigerator and freezer storage, thus allowing the long range trade and importation of fruits and vegetables through all seasons through a great diverse range of climate. This corporation alone has created huge amounts of constant treasure for this wizard and his family. This wizard has then poured these huge resources into magical research to create more fantastic magic items. Now, imagine this magic and wealth creation amplified by the family members for one, two, three, ten generations?
How would such effect the campaign world? I then assume that other people in the campaign world are doing similar things, and that this would make drastic and powerful changes in the way the campaign world looks like and operates. I don't see how, for example, without the DM making a huge "Director's Intervention" that a typical medieval D&D world, with all the magic inherent in the system, somehow remains the same, generation after generation, you know? The economy stays the same, the magic level, somehow, stays the same, wizards stay in their towers and really do nothing, and priests who have the power to make real lasting changes throughout all of society somehow manage to stay the same as well. My thinking says, ok, maybe for one or two, or three generations it stays that way, but beyond that, I don't see how it can. Human beings, let alone other dynamic races, are always ruthlessly pursuing real, dramatic, and sweeping progress. It is from these sets of assumptions that I said, ok, fine. Lets run with it. Use all of the rule books to the maximum. Use the horrible monsters, the dragons, the demonic hordes, and the half celestials. Perhaps the only thing I rule zero is the resurrection and raise dead and reincarnation spells. I use a system of fate points instead, which serves to create a more heroic environment.
I think these kinds of assumptions need to be thought about, and as you mentioned Volaran, need to be taken into account in a fully comprehensive manner if one is going to operate in a epic-level environment that is challenging, fun, logical, and balanced.
What do you think?
Semper Fidelis,
SHARK