This was done in order to keep the transfer process free of charge.
While you’ll be able to upgrade your profile in Square-Enix’s Final Fantasy XV: A Realm Reborn from the PS3 to the PS4 for free, you’ll have to sacrifice your login rights to the former in the process. This appears similar to Battlefield 4’s cross-generational data transfer, wherein DICE stated that you wouldn’t be able to go back to the previous generation with your transferred profile.
In conversation with Famitsu, FFXIV: ARR producer and director Naoki Yoshida stated this was done in order to keep the transfer free. Is there much incentive to upgrading to the PlayStation 4 version? It is presented in 1080p resolution and will support the DualShock 4’s touch pad for use as a pointer device. You can also plug a keyboard and mouse into the console.
Interestingly, Yoshida also talked about showcasing the PS4 version some time near the end of the year, and has stated that it will be “indistinguishable from the PC version”. Final Fantasy XIV: A Realm Reborn is currently slated for a PS4 release in 2014.