"ADC Mains Are Never Happy With the Meta!"
Fact: The reason why ADC mains are never happy with the meta is because the meta is always determined by and based on the most effective way to counter the adc role at any given time. This is because the adc is viable in all meta because of its function in terms of objective control and sustained damage. So the meta always evolves based on the best current way to kill/neutralize the enemy ADC. Thus it never really feels fun to them because they are always the target.
Blame the game design because what I just said is the absolute truth. Its hard to be happy when the game more or less depends on you being able to do your job and you are the number one target every game all game. Meanwhile if you die early the team rages and reports you. ALL while the enemy is typically playing the style/champs that most effectively kill you.
Edit: I am happy to see such a conversation about this topic that hasn't devolved into a bunch of finger pointing. I think we are all in agreement that the ADC plays such a vital role in the game that it really does shape the way everyone else plays the game. Keep it going and keep it friendly!