It really is an excellent analysis, good job.
One of the biggest changes you cite, but its not really given proper attention, is the removal of name level. In all older D&D, 9th-11th level was special in the same way epic level is now special. This was due to the length of time required to gain that much XP and changing face of the challenges faced (first orcs, then giants, now demons).
A while back I remember a thread/poll asking how many people got to 20th level before 3e. It was surprisingly few. I know it took 11 years (off and on) to get to 16th as a thief in 2e. It was not uncommon for games to end at 9th and the dynamic shift in gaming. Hence, a lower-level populace seemed better suited to the game. Thanks to 3e's emphasis on faster advancment and actually using levels 11-20, the low level population seems annoyingly weak. This is doubly true for DMs who love to use human or humanoid NPC villains like evil mages or corrupt priests; if 1% of the population is PC level, I'd say half of them are evil mages, if any campaign is to be believed.
3e's demographics are a response to a couple of fundamental questions...
1.) In a world of animated dead, crushing golems, powerful intelligent swords, and cursed rings, who makes all this stuff?
2.) Where were that PC (my best friend who just rolled up as a new character) before he joined our group?
3.) If guards kill orc raiders for years on end, don't they get the same Xp as I do?
4.) "Don't worry, I can steal every last coin from the mayor's vault. I'm 6th level, what can they possibly do to me?"
Lastly, if the current demographics seem often like a superhero comic (X-men in particular, aren't there mutants who have non-crazy powers and fetishes for skintight latex?), then 1e D&D can be compared to Wuxia (rent Crouching Tiger, Hidden Dragon). There are a finite amount of powerful kung-fu masters in the area, they all know who each other are, and they are constantly doing crazing things (like flying) while fighting each other in spectacular battles while normal people either watch in awe or are mowed down like mooks. When you limit the amount of advancement a group can make, you make them special. You also make them notorious. If Lord Bragg the Anti-Paladin is the most powerful warrior in Helmhome, you better bet a PC knows of him, will find him, and want to kill him. Like Immortals in Highlander, they'd be drawn to each other as the only people who could seriously challenge each other. That creates its own unique feel not simply stated in the DMG, but implied none-the-less by the analysis.
All that said, I applaud you on your article. Good job.
