I believe it first started with WOW…maybe not as obvious though as today. I want to say Destiny is where I first noticed the hollowing out of content to be sold later…but it may have happened before that, I just probably was not as into video games at that period in my life.
Which onto your next point.
It’s more like they are trying to stuff a dungeon crawler into a very shallow MMO lacking any of the typical QOL MMO systems.
I don’t have a problem with them trying to make this vast open world…the design is nice…the execution is horrible.
The static side quest, I agree should be more dynamic, but more importantly tied to the lore. Not stuff like…“I lost my camel…help me find it” 
There was so much they could have done here with new ideas…instead they designed the world and map and then stopped. I still think this has potential for a wider audience.
On the ARPG side…the lack of challenge outside of bullet sponges at high end to me is the biggest offender. All the enemy types become similar to some degree and you really don’t need to understand any mechanics to be successful because you will be so OP against the content till you are not.
I actually think in this regard the game was better on release than it is today. They can still improve this as well…but it doesn’t seem like they want to…as they believe their audience needs it like this.