See, and that's why I think a reboot would have worked better. You still have to know about Unther and Mulhorand's ruins, even if scaly Dragonborn overrun the place. You still have to know about Sembia's merchant past, even if it is conquered by Netheril. You have to know why the Spellplague sucks by knowing all the stuff that happened in the past, and it still makes for adventure designing to be canonically a pain in the neck. The canon wasn't erased, it was just added to with a new time of troubles.
For example, now instead of having to know about Bane, you have to know that Bane was replaced by Cyric, Bane was ressurected, and that Cyric is now banished from Faerun. It is a long way to go just to get back to the status quo.