Well, server don't cost as much as you think even for an MMO, one of the reason they are so popular to develop these days ,even a small paying user base generates a decent profit. The other thing to note is that SE is not really loosing money on this game, you still had to buy the software.

Obviously I'm being a bit optimistic saying we'll have to pay starting next September, but I really don't think it's in SE's interest to to effective relaunch the PC version without a new hook (ie. added expansion) to draw in a new audience. I also don't think it's a good idea to start charging the users who were loyal to the game through thick and thin before the relaunch, as I don't see SE giving the current users the expansion for free, I know I wouldn't give it away for free; having current users buy the expansion is what's going to make them back the revenue lost from the extended free play.

Form a Marketing perspective it also makes sense, SE want this to be their flagship MMO and a competitor in a market that about to go to war (TOR vs. WoW/Bizzards next MMO), they have proven that they're willing to do what it take to make sure it succeeds. However without the continued good will of the current user base; plus they need reviewers to take a new look at this game once it's relaunched, which means they need users to be the driving force behind the interest in the game.

Without both of those SE might as well pack up shop and start to develop FF XVII as their next MMO, heck even if what I say is right, FF 14 would be starting out forth in a three man race, SE is going to have to prove even after relaunch that this game can stand up to the big boys that are coming on the field or are already there.