Even as a casual player, I'm on the "make casual content harder to raise the general skill level" side of the fence.

However, looking at some of the responses here,I think, some of the more skilled players need to consider the following:

1. If OP has been playing MMOs since the 2000s, their memorization ability, pattern recognition and reflexes, might have deteriorated significantly.

There are people who play this game because even without the combat content, it's an amazing world with lots of awesome non-combat content. Simply making the game harder, to raise the general skill level, does seem like a way to lose subs for people like that.

Of course, OP could try getting friends,FC,etc to help them out on content which they find challenging.

2. Devs need to reconsider one-shot mechanics, which are dependent on latency. As other comments have pointed out, I've lost count of the number of times, when it seems I've clearly dodged something, only to go "Oh, I'm dead...". Having to factor in lag while doing increasingly complex/multiple mechanics (from the casual perspective) does seem 'unfair'.

3. Your hardware matters. I don't do any of the level 70 dungeons anymore especially those with heavy lighting/water effects. Even with my graphics settings turned way down, I get unplayable fps. This is on the player to upgrade their hardware.