My server is in a Japanese DC, and many Japanese people want to make sure they know the dungeon before they run it with strangers, so they don't mess up and are embarrassed. The fact that you have to execute the mechanics properly, or you have to restart the fight is actually a good point. In a team with players, you can get carried and never learn to do it properly. With Trust, you'll not finish the dungeon until you learn the fights.

The fact that Trust NPCs don't judge you, tell you to hurry or think bad of you for messing the same mechanic up 3 times in a row is huge.

And then, sometimes you're in the mood to play, but don't want to deal with people. Trust is fine for that.

And last but not least, YoshiP already said they'll expand the range of Trust-supported content.