I think the big thing here is a very old philosophy that new developers don't get. "If it isn't broken don't fix it". In other words, open world grinding has been a staple in mmos for years and people (the majority) were content with this because it promotes finding a group of people at an early stage of the game and basically levelling with them all the way through to end game, which usually causes said people to become great friends and probably become a core group to start their own guild which becomes successful because said core group members have spent weeks leveling together...

My point here is I understand these developers want to create next generation games and you know what, in theory Fates and Duty Finder aren't bad ideas, but to create them in a way which totally destroys the old ways of levelling and playing completely ruins the experience. Think about it, with duty finder and fates, what out of these two activities cause you to want to remember the people you do them with? To make them long term friends? And i'm not talking about end game, i'm talking about the GAME from beginning to end. Nothing in those activities promote friendship. It's a ridiculous oversight to have gotten rid of open world exp grinding in my opinion.