When you reach the maximum level, any experience you gain is wasted. Now, some of the quests you get will only give experience, so if you do them at max level you get nothing (except a sense of achievement and continuation of a great storyline).
So, what if quests gave gold instead of experience when you are at max level? That way there is some incentive to do the quests instead of just save them till a level cap increase. It would also alleviate some of the lack-of-gold concerns that people are having.