To play PS2 games on PS3s now, all those games would have to be recoded, since the required hardware to support the software has been removed, and likely the system doesn't have enough processing power to be able to do live software-only emulation of the PS2. SE has already stated they are not going to recode FFXI again to move it to another platform, or upgrade it to use a higher version of DirectX on Windows, since it would be similar to coding a new game, and so they'd rather put out a fresh new game. They've already announced yet another MMO on top of FFXIV, and FFXIV is still being ported to PS3. FFXI only has a small development team remaining, and it's not the people that originally coded it. They're not going to recode the game when they can't even fix some of the issues existing in the game at this time.
Doing an American disc print run runs into economy of scale. It costs more per unit to produce a small run than a large run. The larger the production run, the cheaper each copy of the game is. PS2 doesn't support regionless discs, so they have to do a seperate procution run for each region of the game, and they have to certify it with the local ratins system, which costs money for each submission. Also, unsold discs will cost them for distribution, if any are leftover. Japan is a physically smaller region for distribution, compared to USA/Canada, and they have a larger population with the equipment. It makes sense not to produce American discs.
However, I'm working on a way to transplant the installed files from a JP PS2 HDD to an NA one, so hopefully a file check will finish expansion installation (I own a PS2 from both regions with FFXI installed), as there is a program to open the partitions, read the files/folders inside, and copy them between the HDD and a USB flash drive.
Although most people have moved on, here's one of the articles mentioning the cancellation of XI on the PS3:
Quoting from the article:
"Initially we were in talks with a representative from Sony [to achieve this], but it appears that that person quit," said FFXI producer Hiromichi Tanaka, inducing laughter from the rest of the team. Tanaka also explained why it's a little more complicated to make the PS2 version work than, say, simply releasing some sort of patch or update for the PS3. "[Current] PS3s don't have PS3-side PS2 emulation, and it doesn't look like Sony has any plans to address that issue. For that kind of thing to even be conceivable, it would have to be on a disc. Digital downloads wouldn't work for this. The disc has to be in the system for the emulator to work."
Interestingly enough, Square also mentioned a Vita port, but that too got cancelled: