It depends on the subject. For classes/subjects that are very terminology-heavy, with a lot of dependencies between topics, memorizing things is a pre-requisite to the "deeper" understanding, especially under time-constraint of a semester or whatever. I think most people would agree that it's ideal to "naturally" explore a subject in order to get a deeper understanding of it, but one can't always be expected to 1. Be able to deploy that "curiosity" for all subjects at any time and 2. Be able to adequately achieve competence in a subject within the given timeframe