Because as much as we want bikes to be treated as "vehicles", a bike is just different. A bike is not a pedestrian, and its not exactly a vehicle either. A bike is human powered like a pedestrian, the rider is more exposed to the elements like a pedestrian, a person on a bike weighs about the same a pedestrian. A person on a bike has the same level of visibility as a pedestrian that is very different from a driver in a vehicle. A person on a bike is more maneuverable like a pedestrian, can stop as fast as a pedestrian(when going slow). Rolling up to an intersection with sensor controls on a bike frequently doesn't trip the sensor the way "vehicles" do. (If I have to get over to the pedestrian button to get a light, I might as well act like a pedestrian.)

Going through a red light has nothing to do with "feeling silly". Its just as safe to roll slowly through a red light on a bike as it is for a pedestrian to jay walk. I don't really see a difference. I guess if you're a real stickler about jaywalking, then you should sit and wait.