Such objections may arise from a belief that the more you know about something, the less there is to know, and the more boring and predictable your world becomes. The opposite is actually true. The more math you learn, the more you realize there is to know and the more magical and mystical the field appears to you. The more you know about music, the more you want to know. Perhaps people's adverse reaction to the idea of controlling consciousness arises from the word control itself.
Control has negative connotations for some people.
The pianist never truly 'masters' the piano. There is always room for improvement. In fact, the better you are at an activity, the more room for growth and improvement you find. The same is true of meditation's effect on the mind. The better you get, the more complex and mysterious your mind becomes, expanding gradually toward God or the universal consciousness, or oneness, or illumination, or infinite complexity, or whatever your belief system ascribes as the goal of your life.