It is also a matter of playerbase being lead to believe one thing and then the delivery falling so flat that even the strongest of supporters are left wondering what happened. False promises are worse than no promises at all, and are a reason why players get discouraged.

I shall list some examples:

What was advertised: New ranged class, machinist to add spice and variety to ranged support dps, presumably mobile and able to shoot on the run.
What we got: Homogenization of bard and machinist, and turning them both into turrets, killing mobility.

Advertised: Relic quest that would be different than earlier relic quests, less grindy, actually fun.
What we got: Even grindier quest that is not fun at any point.

Advertised: Specialist crafters would help expand capabilities of people that choose to specialize in the 3 fields out of 8.
What we got: Each specialist class has exactly the same skills that cost high cp and is used as a mechanic to gate recipes rather than advance players.

What was advertised: You can marry the character of your partner/friend in game.
What we got: You can in fact do so, but in order to have customization and a mount you have to pay real money, once per character.

What was advertised: Any event art that features designs that look really nice (like the red hooded miqoute in winter event).
What we got: Nothing that looks like the art