Reading the most recent "Letter from the Producer" (#51) and the themes planned for the next "Live letter" (oct.19), it seems as though they're not even addressing the issue. Based on the fact that it's an "accepted bug" and also a topic they did address back in v1 and v2 beta, I have formed the following conclusions.
- Square Enix is aware of the problem but does not have a working solution for it as we speak.
- Considering how long they've been aware of the issue, that they still haven't come up with a solution means one of two things: they either don't think this is a serious issue, or they simply don't know how to fix it. The latter could be resulting of two likely constrains: either a technical one, by which they don't have the skills necessary to improve their code; or a budget constrain, meaning they don't have the cash to muscle up their datacenter enough to circumvent this 300ms check (we all know that, to reach acceptable "fixing" standards, this check should happen at least 10 times more often, in the vicinity of 30ms or less).
- Considering the above, Square Enix knows that simply admitting that they can't fix the issue would be a very short-termed relief: while players would appreciate the honesty at first, they'd likely be very hesitant on continuing to play an online game that is that much sub-par in terms of responsiveness. Therefore, they just don't say a word about it, preferring to be oblivious to the issue, at least publicly.
- I could think of a few ways to at least improve the situation, typically by implementing client-side prediction, as most AAA online games do from day 1; but again, considering all of the above, and the fact that rewriting netcode is by no means a small endeavour, I wouldn't get my hopes up for such a design improvement before 3.0 at the very best. If Final Fantasy XI is any indication, game-breaking issues of this magnitude may never be fixed.
Should this be true, it is my contention that it's probably the worst way to address such a game-breaking issue: try to bury the issue under the carpet, and probably not even work on it (or very slowly) behind the curtain. They should not only make a grand statement saying that they're doing something, but also and foremost invest heavily into solving one of the most worrying aspect of this game, bearing its long-term future in mind. Should they not do that, most players will simply move on to other games, not without mentioning publicly on various forums/comment threads/to friends that "FF XIV is nice but the network is broken", and should other players still try this game after that, they'll realise soon that indeed the network part of it is broken and, simply put, they'll leave as well.
This game could have millions of subscribers in the long run, it is that good; unfortunately with such poor responsiveness, it's unlikely to be anything more than a niche akin to FF XI, in the vicinity of 500k regular subscribers. For a franchise (IP) that sold above the 200M mark in its 25+ years of existence, I'd call that a failure. Wake up, SE.