Well FFXIV is certainly not the 1st MMORPG to recover from a really bad launch and release. This has already been discussed before but I can think of 2 MMOs that have been able to recover in the past 9 years. It is possible, it is just extremely difficult to do so especially with how unforgiving the MMO community is especially amongst fans and other factors as well. EVE Online is probably the best example, there are reasons as to why they were able to pull it off (which has also been discussed). Also note: nothing FFXIV is doing is a "1st" in MMO history especially as a P2P fantasy MMORPG.
The gimmicky Version 2.0 2.5 3.0 has already been used by other companies. A few companies have even revamped their engine while others have added literally gigabytes of updated content/patches. The main difference is to a varying degree. History has shown that these methods (as well as others) have almost never been able to gather a substantial amount of players and keep them for the long run (directly connected to a bad release/launch). Companies keep trying simply because the other choice is shutting down or going through different levels of F2P. I am actually looking into this more in depth. FFXIV may be the 3rd company in the past 9 years that might have a huge comeback.