I found a great post about bored employees and their level of job satisfaction. This isn't meant to drive employees into the ground and give them more work then they could possibly handle, it is about giving them meaningful work that once accomplished they have a great sense of accomplishment. After all, isn't that what most humans want?
Part of most employees' "deal" is to feel valued. This has a personal and performance component. They want to certainly be treated fairly and with all the common courtesies (like management not ignoring them, not being treated as a second class citizen, etc.) as well as having their current and future development needs met (so they can achieve their own personal work-related goals – whatever they may be).
Employees who are bored (reporting "too little work") are often doing work for which they are ill-suited, or have jobs that are poorly designed. As a result, they have by far lower job satisfaction, sense of accomplishment, and pride in their employers compared to all other workers. All in all, they feel less valued.
Have you had a job where you get bored? Watching the clock till the end of the day? Now think of a job or a time that your job was so engaging the day flew by and you voluntarily stayed late because you wanted to finish the task. Not because your boss made you or because you would get overtime, but just because you couldn't leave it undone? That is a tremendous feeling of value and satisfaction that we need to bring to ourselves and others we work with. There is no way that you will only have to deal with the fun things in your job, but everyone should be able to incorporate more of those tasks that help you leave at the end of the day saying how great it was. What would your workplace be like if more of your co-workers felt that way? What would you be able to accomplish?