Maybe this has been addressed already but I just noticed this from Patch 1.18 notes:

[dev1085] Main scenario quests and subquests will now award skill points upon completion.
NPCs offering quests which grant skill points as a reward can be identified by the blue exclamation marks over their heads.
* Completing a quest using a class ranked lower than the one recommended will result in a smaller skill point reward.
The Part in Red is what bothers me. Isn't this backwards? Shouldn't it be the other way around? If you can complete a quest lower than the recommended level (without help), shouldn't you get more exp since it is more difficult?

On the other side if you grind to r50 then go back and complete a r24 quests, shouldn't you get less exp since it is easier?