It's storyline reasons why they couldn't, at least for Blue Mage, Corsair, and Puppetmaster. The primary Dynamis areas are an alternate dimension where the Beastmen won the Crystal War. Since Aht Urhgan, as a whole, didn't participate in the Crystal War due to their own Beastmen problems, so it wouldn't make any sense for them to have weapons from the Crystal War. The same would be the case for Rune Fencer and Geomancer, since those are coming from a region of Vana'diel that, for the most part, had been isolated from Quon for years. Sure there were some people that traveled back and forth between them, but Adoulin was a very isolated island, to where we're just now gaining access of any real extent to it.
I also think that people are, as a whole, growing tired of the alternate dimension/timelines that dominate FFXI so far, and adding yet another Dynamis or series of Dynamis would probably not bode all that well, especially if they ended up being only useful for those new jobs.
I also don't think we need another new line of "ultimate weapons and armor" so soon after Empyrean. The possibility might be there, but I think their time would be better spent getting Adoulin into prime working order, balancing the old jobs and the two new ones (which will be an ongoing process) and things like that before adding some new "Legendary" equipment.
____________________________
Lady Jinte wrote:
Vlorsutes' Negotiation Skill rises 0.2 points
Vlorsutes' Observant Parent Skill rises 0.3 points
Vlorsutes' Argument Diffusing Skill rises 0.1 points