It's the curse of the MMO time bubble. This was a similar thing in FFXI when the Crystal War was constantly referred to as having happened 20 years ago, even with expansions released years later. So while we can infer time is indeed passing from lore hints and dialogue, it will be passing at a crawl as to not force necessary dialogue updates. If this seems jarring now, just wait until we're in 6.0 and Bahamut was still "5 years ago".