I used to feel very in-control of my own mind, but after intentionally sitting and monitoring for thoughts, labeling those thoughts, etc, I became sensitive to how thoughts can really come out of nowhere. You can't predict what you will think next. That strikes a little deeper than a nature/nurture argument where you might say "oh, I just behave a certain way I guess, its in my genes". You start to wonder if you're just being forced to watch the movie that is your own life.
I personally feel like my life is a mostly-good movie, and there's reason to predict it will continue that way, but for many people, they're stuck in a bad movie. Some people may feel imprisoned by that. But not feeling in control can also be liberating, depending how you look at it. So I definitely agree that it's a double edged sword, or that YMMV.
(Overall, I've enjoyed meditation, and I try to do it about once a week, just to remind myself that there's another mode of thinking that's available to me.)