The biggest problem I have with leveling too fast is that it's too easy to outlevel a skirmish before you even get the quest to do it...that leaves you stuck not being able to do it and not being able to get certain achievements. (Plus if you are a completionist OCD like me...it makes you want to re-roll, ugh!)
This issue is also a dealbreaker for me. I want to play ALL the content, at my pace! I'm only lvl 22 and have already missed out on doing 1 skirmish, about to outlevel another, and haven't even come close to reaching the quest to do it yet. I've found areas where there are npcs but no quests, so it seems I've outleveled…