(Gotta say first that I love these kinds of discussions; Civil and beneficial in one way or another)
I agree with your post, and I really like how you summed up the two systems at the end there, but FFXIV consists of both systems in one.
That being said, I think I may finally be coming to understand here, so let me know if I've got this right:
The value of gil in the player driven economy will rise if everyone is knocked down by the same percentage? It seems like as far as the static system goes, that still relies entirely on the static system's parameters. But from the perspective of those who only earn their gil via the player driven market, I think I can finally understand why a 10% drop across the player board would be preferable.
Edit: Preferable over just a shave off the top of the cap, and why it'd be preferable to leave the cap as it is overall.