Enkidoh has the right of it (as is often the case).

Think of FINAL FANTASY XIV as a TV show. Answers was crafted for the purpose of being the theme of the first season. To keep the metaphor running, the pilot bombed and it got canceled after a few episodes, but people saw potential and the network didn't want a big black stain on their flagship brand, so they brought in a new director/producer to redo the first season. Because [Version 2.0] is also technically [Version 1.0-B], the theme remained the same. Answers is thus used in the Coil because it's the epitome of the first and last episode of this re-done first season. A lot of people forget this when they try to interpret the meaning of Answers' lyrics, as well, and end up trying to tie the vaguer parts of the song to all sorts of recent and future developments as opposed to the game's intended Season One foundation. Season Two was likely always planned to have a new theme song, but they didn't expect it to be four years later with a new game and a new team structure. This is one of the reasons why HEAVENSWARD is such a big deal - we're finally moving past Season One.