I'm honestly surprised so many people take issue with the difficulty setting.

I've only started to play around two and a half weeks ago, but I only found myself using them if there was something I didn't feel like dealing with. The MSQ instanced quests are honestly pretty annoying, they're slow, don't require much skill other than dodging AoEs and get really tedious after a while. Most of the time you don't even need to worry about healing since you have a healer with you, or some broken-ass way to heal in the middle of the fight, since the designers can't account for when people don't have self-healing on hand.

And keep in mind, I clear about 95% of the instanced moments I've come across on my first try. They're not hard. The ones I don't, I just put on very easy, because I more than likely died because I wasn't looking at my screen for a split second at the end of the fight. I pretty much beat it already, so putting it on a lower diff to just make me blitz through it a bit faster isn't much of an issue.

I can't really speak for some of the later content, but I just dislike the instanced moments in general. They break the flow of gameplay to me, and I'm only really interested in cutscenes. I think the difficulty settings are a good addition, especially if Echo was in place before this point anyway. It just saves time, and I doubt players really get much worse from it since they're so easy to begin with. The biggest threat to you inside of them isn't the enemies, it's the boredom making you slip up.