Board Thread:Questions and Answers/@comment-5105419-20131205130839/@comment-1173941-20151208140345

The difference is that the original FMA anime (2003 by the way) aired while the manga was too early in the story, and they knew it would catch up too quickly, so it diverged intentionally. The reboot was to follow the Manga more closely, considering it was closer to being done at the time.

SAO isn't like that at all; the anime pretty closely adapts the source material, despite the few changes between mediums (though, they're the kind of changes that always happen in adaptations.) There is simply no real reason to fully reboot the anime; it could have been done better, sure, but there's no reason to start over. At best, maybe have OVAs for content that was skipped