I don't know how big the dev team is but I imagine it's quite the strain to be developing all this content alongside another full expansion. WoW didn't add new content this quickly iirc. It's like that triangle of project mgmt thing. You can either have it fast and good but not much of it or a fair amount of good stuff but released much slower. Or you can have lots of content fast but then it's terrible. You can't have lots of good content at a fast pace.

Add to all that we're also getting expansions (so far) way faster than WoW did. Also, they are trying new things. Diadem (that was trash tho), Aquapolis, Palace of the Dead. All new things a and then forum posters dookie on it immediately; which I imagine is quite disheartening.

I can't speak for anyone else, but I'm alright with the content right now. The game became much more enjoyable when I became casualcore. Trying everything a bit at a time that the game offers is better than trying to ex/raid all the time.