Even with very invasive techniques (chronic implants), the reading of motion signals for example is very problematic. One of the first devices to do that is the http://en.wikipedia.org/wiki/BrainGate . It requires substantial training and retraining because of brain plasticity. Still, these are major breakthroughs, and hopefully we will be able to find a reliable and usable signal, but i agree, EEG is too bulky for that purpose.