Actually, what the letter is talking about is whether or not they were going to keep the servers for XIV live after November 11th, even if none of the data is saved for the relaunch.
So it's not that they're tossing all the player data, it's that they're looking at a hard boot point, I guess, for the Realm Reborn. The producer was apparently planning to shut the servers down if less than 30% of the players voted to keep them open, and use the player data accumulated as of November 11th as the starting point for RR.
And in typical fashion, while nearly 70% of the rest of the world said they wouldn't care to play the game after November 11th if the data was just going to be wiped out when Realm Reborn hits, the JPs were a hair over 50% in favor of keeping the servers on even if there's not much point to playing.
I swear, the Japanese fan base killed XIV by not being willing to tell SE when they were fucking up during the alpha/beta.