Which part of there being another 3 months of optimization do you not understand? If a game is not optimized to run smoothly, it is by no means an indication that it cannot be done. After everything this team has accomplished, one would think that they deserved a bit of faith. With the way that the new engine has been designed, the PS3's hardware is more than adequate to run it on lower settings once the software (the software currently optimized for a PC) is properly optimized to run on it.
And nothing was downgraded. The graphics engine is simply less convoluted. The engine is preset onto lower setting for the PS3 to avoid the hardware limitations that held back the FFXI graphics engine. The FFXI graphics engine could still be registry hacked to display considerably better than the configuration software allowed for.