I don't know that early quitters are due to normal content being too easy. I was ready to tap out multiple times during ARR because the entire experience is boring AF and probably the single worst MMO leveling experience I've ever had as a 16 year MMO veteran, which had nothing to do with the dungeons and everything to do with the MSQ being tedious, jobs being bare bones, and the "gameplay" amounting to teleporting around clicking through endless dialog with hardly any combat between besides the occasional dungeon/trial.