If Blizzard did what you explained WOW without question would succeed. Like you said make all zones relevant and maybe give us 2 or 3 new Korthia type zones every expansion. We will see this is the first time on the forums and social media since I’ve followed it that WoW doesn’t have a lot of defenders anymore.
What’s crazy is even the hardcore flex get good players are now realizing the game isn’t fun without casual players having fun.