Is having a good time reward enough for playing D&D? Hell no! I want treasure and I want XP. I’ve earned it. Gimme, gimme, gimme. I’ll admit that as a player I fall pretty squarely into this camp. Having a good time and socializing with friends is a great part of playing D&D, but what I look forward to most at the end of the session is the reward. And thanks to the mechanics of 4e D&D I’m rarely disappointed.
The rules for rewarding players are so simple and streamlined that I know at the start of the night what I can expect by the end of the night. I’m not saying that this is a bad thing at all. By having some general foreknowledge of what I’m risking my PC’s life for, I’m more strongly motivated to rush headlong into a fight with a dragon or attempt to decipher the ancient glyphs protecting the entrance to the lost treasure trove.