Honestly, I attribute at least 45% of the Xbox's early success to the popularity of this 2003 JRPG. One of the few series to jump ship from PlayStation, it paved the way for both the genre, and more importantly- LORE, to come to the best console of a generation.
Though many games have emulated or tried to copy it since (Final Fantasy 12, Sea of Thieves, Assassin's Creed IV: Black Flag) - none have been able to come close in terms of the immaculately fashioned experience of TideWater.
The Pirate class was a strong step forward in not just the design of JRPGs, or even RPGs- but gaming as a whole. You can see the impact that it had on the scene with the release of "Sid Meier's Pirates!" the very next year- western developers were eager to try to ride on the coattails of this massive success, but forgot the most important aspect that tied all of Pacts together - the LORE.
It's much more than just a game - it's a revelation.