School boards can be flawed, of course, but billionaires and nutjobs like the Kochs who want to bribe and control elected officials like mayors who then pick their cronies as superintendents is vastly worse.
This comment from the Ravich blog nails it:
School Boards have been under attack for a long time. In this case it is probably costing those that would be king or queen too much and they are not wanting to have to go to every state and manipulate and influence folks. School Boards are just another nusiance factor to get out of the way when you want absolute control. Remember, respect of the other guys opinion does not seem to mean much these days. The more layers (no matter how good you may think they are) taken from the American checks and balance options, you stand to lose your ideal of what American life is or should be. Stripping the layers of citizen voices out of each of our systems of governance and having a small group of very self important overseers watching over and governing every decision for us is fool hearty and dangerous. You may not like school boards but they are important to our process for many reasons. Stand behind and with them. Go to your school board meetings and make yourself known and give your input. They and you are important to who we are as a nation.
In other words, it costs too much money to bribe every single elected official, so why not streamline the process?