XI released in JP a year before the US and didn't have the xilart expansion. When it shipped in the US it came with the xilart expansion and the cap was raised to 75 and it stayed there until abysea came out a decade later or so. The cap never raised before that.

No imagine playing XI in japan with a level cap of 50, no SKY and no xilart missions. That's pretty much what we have in XIV right now. The difference being that it came out for JP, NA, EU etc all at once. If it were like XI we'd still be waiting for launch till aug 26th 2014.