In a followup post to his earlier discussion on progression, Morrison talks at length about the decisions developers face when it comes to providing players with a steady diet of dings and digital pats on the back, while simultaneously making it seem like something worthwhile is being accomplished. The post contains a number of interesting observations, among them the notion that most modern MMORPGs parcel out their challenging content in sideshows that are entirely optional (raids, dungeons, etc.) and, in many cases, tangential to the main event (questing and hunting).
While it would seem to be a relatively simple matter to add occasional challenges to the leveling treadmill, Morrison cautions that care is needed to avoid alienating segments of your playerbase. "If you are going to be able to inject occasional challenge or difficulty spikes into the standard progression as well, you need to have thought about it to make sure that it won't become a bottleneck, and that it will survive a review," he says.