Black Desert Online did this really well, but it still failed because of corporate greed and incompetent shitdevs. Naturally, the lesson learned from its failure wasn't "don't be a shitdev." Instead, the MMO genre learned that "gAmErS doNt wAnT oPeN wOrLds ackshually" so we'll probably never get anything like that ever again.
XIV is basically a lobby waiting game. You wait in your house or one of the main city states until your content pops in the queue. Then you go to another instance to do it. The game makes money like this and there's no reason to revamp it and take risks to change it. Sure, the overworld is dead, but who cares? The people spending the most money never leave their goonshack anyway.