Explorables are designed to be done by the level you can start entering them. It's obviously harder, but don't forget that some of them originally awarded sub-80 gear from the vendor.
So I wasn't sure if my thief I made just before patch would have the new trait unlocks or not since he was below level 10, but now that he's 30 I can see that i have all the old traits unlocked already. I'm questioning if I want to remake the thief to test out the trait unlocks or whether I should be thankful that I'm avoiding them. I have enough tomes and level boosters to bring him right back to level 30. I just don't know if its wise.