When people are having fun, they push the limits of the system.

They're pushing themselves for its own sake, so they're more likely to naturally hit the ceilings of the system.

When people are doing something because they're told to, they're more likely to just stay on the established paths.

If you're trying to create an open-ended system, you want one where the initial users are pushing the limits.

If they aren't, you might just be staying on safe paths shown off in the demos.