Regional servers I feel are a horrible idea. One of the best thing about XI and XIV are the global servers.

The only pro I see is lag reduction, and if they are still in Japan the lag will not be removed. So unless they put up servers in the respective regions/subregions it will be completely pointless to do. And the game would need millions of subs to do this effectively without having player shortages as well which is another hurdle.

The cons are a worse economy, huge periods where the server is all but vacant (outside the regions prime time), and a much higher volatility if people from a region mass exodus like they tend to on NA servers when a new mmo comes out. Look at the old unofficial NA servers in XIV now mostly ghost towns compared to JP unofficials.