It's the first adventure in the 4e "adventure path." It's B1 Into the Unknown, it's T1 Village of Hommlet, it's Sunless Citadel. It's not a combat demo, it's not a "taste." Once the rules are out in a couple of weeks, KotS will continue to be published and exist and serve as people's intro playing D&D. There's plenty of roleplaying material in the adventure, possibly more than there is in most published adventures.
Sunless Citadel wasn't hobbled. It was released with the rules and contained the information necessary to run it.