For any invasive surgery, especially when messing around with nerves that are so close to brain on young children, involves risk. There are existing risks in the procedure, enough to cause disastrous results for the rest of the child's life. There is no undo or redo. When the implant fails, all of the child's residue hearing is lost forever. The child is even more deaf than ever. So, now what?
I work at an environment with many teenagers that has failed implants. They became erratic, lonely, and depressed. They couldn't speak or sign well. It is sad to witness their psychological struggles because they are travelling toward a place that are not accepted by many - deaf and hearing. The saddest part is, they are not usually accepted by their immediate family members. They continuously wonder, do deaf people have right to exist?
The implant technology is amazing. The processing power and channels has improved tremendously. The size of the device has became smaller and durable. These hardware advances are wonderful, however, the "human software" part hasn't advanced much to "try and catch errors and exceptions." There are ways to better handle "bugs." Instead of panic-and-fix-by-brute-force-patch. Learning a new language, celebrating diversity, developing tolerance, studying cultures, and respecting differences are critical soft skills in many situations, especially interacting with people who are drastically different.