How did they abandon them? Was there any indication from Blizzard they meant islands to be anything other than what we have now?

They must have put tons of development time into things like hiding the drop rates, making specific mobs drop the rare stuff, and having all the various sets of mobs / islands combinations for how they spawn. The AI is also reminiscent of the ToC AI they made in Wrath that does behave fairly distinctly from other NPCs which is... cute? Thats all the faction champions ever really were either.

They definitely aren't what the players might have wanted, but considering the consistent thread across all of BFAs systems of many players not being content with the systems design Blizzard put in place... that just sounds par for the course on islands.