Dangerous thoughts. Upcoming in this train of thought: "I think disabled people don't have the right to consume food and energy, because they don't contribute to society."
IMO that's not really on the same train of thought. There's a difference between voting and having right to food. It is also not about utilitarism, because additional votes are like licenses you need to do specific jobs. One big problem with giving more votes to educated people is that educated is something hard to define. Passing a special, unique exam ? Yeah why not, but the contents of this exam would have a huge factor on the votes. By definition it should be fairly dynamic to remain fitting with the times, but also very hard to change in order to avoid electoral manipulations.
Now, the core problem is that there's no guarantee that more educated people do not see voting as a chore, a way to vent their daily frustrations or get revenge on the government.