Mindfulness, in and of itself, is not the problem. The problem, perusal, is expecting a "miracle cure" without actually doing "the work."
A 7-8 week training class on stress-reducing mindfulness practices is not going to deliver long-term results without the reinforcement of mindfulness coaching. This is like expecting to become a concert cellist after 7-8 sessions with a cello teacher. It's just not going to happen.
For mindfulness to have the intended results in the workplace, organizations need to do more than hold weekly training classes.
It's best to look at mindfulness as a "way of being" rather than the latest leadership skill.
From my perspective, mindfulness is the prerequisite for consciousness. If we are not conscious beings, then we are acting like unconscious neurotic zombies.
Furthermore, the best benefits of mindfulness in the workplace relate to the "what" of mindfulness, not the actual skill of mindfulness. In other words, what should you become mindful of?
The answer to this question will determine the "real" results of the mindfulness programs.