They pay taxes and buy things in the state. I also find it hard to believe that they were not there to serve some sort of purpose, everyone has a slow day every once in a while. If they were just playing around for 8 hours every day than they should be let go and so should their managers for letting it happen. So in that instance I agree with you, if there is a person filling a job that didn't need to be filled than they should go but I am not for getting rid of people that do actual work and make a contribution.
Paying taxes doesn't do much good if you are paid from taxes. Buying things in state I'll give you though. And sure, they are supposed to serve some purpose, and some do..but many are either way underutilized, or are doing something that there really is no need for a person to do. As far as letting them go..even if they aren't doing anything, that's rather difficult. I've heard horror stories about how difficult it is to let go of a government employee..it takes a relatively substantial paper trail. In fact, on all the projects I've been on, when someone who's in over their head was in a management position and causing problems on the project, that person would usually be promoted to get them out of the way. Generally because they won't accept a lateral move, and firing them is difficult.
This leads to people that are in way beyond their level of expertise, "in charge" of projects and hiring people. Thus, people that are horribly utilized or placed into positions they shouldn't be. It also typically results in the contractor running the projects, bidding things up, and a government lead who's in no position to argue because they simply don't know any better.
The problem runs deep, and there are no easy answers. For the most part I think people mean well, but the system is flawed.