Our brain was not built to directly transmit signals nor to accept input wires to read / write signals. I am sure one or the other can eventually be overcome safely. But we are not there yet.
The corpus callosum is pretty much exactly a signal bus between the two hemispheres. Granted, it's a 200-million wire bus, but it basically transmits entire "thoughts" between the hemispheres. I think the dream brain interface would be a tap on the CC.
