Why now? Why only PC ??
I hope there'll be an iPhone version of this.
My theory is it's mostly about them establishing their digital store front. Publishers are starting to get the clue that the future of game delivery will be all digital - and so they're scrambling to setup their own digital sales infrastructure because they don't want to continue to giving a healthy chunk of their profits to Valve.
Square doesn't have some big new PC game to get their foot in the door with people like EA did with Origin and BF3 or TOR. Next best thing is to re-release one of their most popular games of all time in space where it's been very difficult to both get a hold of and run.
I have to think that a lot of people aren't going to be making SquareEnix store accounts for this.