Dungeons can be considered easy to beat for some players. And it really is with a thrall support. And it’s ok, because you have to beat the same dungeon many times to craft what you need, so it can’t be very difficult.
Why don’t let the first time harder than the others? For example, when you beat the final boss, you get a new weapon that helps you to beat the dungeons again easier than when you don’t have this weapon. So, beating the dungeon without this weapon is a really challenge objective. And after you get it, you can redo it without too much trouble just to get loot.
It could be a skill you learn, a “magic protection”, anything that makes the dungeon easier for the next times you play.
And Funcom could “sell” (microtransaction) this resource to those who don’t want to make too much effort to beat the dungeons first time.