0.3 to 0.6 s ping on an MMO is debatable. For MMOs like WOW, Aion and RIFT that depend on quick reflexes for interrupting spells and the like, it's inacceptable. Pings that high will get your group killed. For FFXI it was fine, because the combat was slow enough that it did not kill you most of the time. FFXIV is just on that threshold of needing good ping to be able to play it.

By the way, here's a ping and tracert that I just did from Cambridge to Shanghai. This is round trip, and is considered unacceptably high by a company that does not provide services that become poor quality with higher latency.

--- *** ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 6003ms
rtt min/avg/max/mdev = 282.348/282.773/283.595/0.755 ms

# *** (***) 282.609 ms 282.369 ms 282.426 ms

So I'm guessing the 0.3 seconds that Yoshi tossed out was from people playing outside of Japan. That's normal and understandable.

If it was from people playing in Japan, then it's completely ridiculous and they need to put some serious effort into getting that fixed.