I am a big advocate for user control. In my opinion, there are too many e-learning courses that do not allow users to navigate through the content as they wish or need. Lack of user control is contrary to many principles of adult learning theory. Allowing user control provides self-directed learning and allows users to determine their learning needs and what is relevant to their needs, all of which are important concepts in adult learning theory.
Plus, if user control is not allowed, a designer is usually limiting his or her courses to being very linear and excluding many opportunities, and benefits, of using experiential learning, situational or branching simulations, educational games, etc.
I have had people say to me, "If you allow user control or make it non-linear, users will not read all the content or just go straight to the test." I am a realist, and there are always people who skip straight to the test/assessment. All the more reason to make courses very engaging, interactive and relevant. If done well, users will read and digest the content. If they still skip to the assessment, but the assessment is a well designed and valid measurement of learning, recognition for their need for the course will happen. And if they passed the assessment, then maybe they were already proficient with the content, capable of meeting the course's objectives and did not need the training in the first place.
Next time you design a course ask yourself, "Do I want to engage the learner and help guide them through a positive learning experience or dictate a learning experience?"