I'd like to see your source data on this one. It may very well be true, but I have a hard time believing it. You also mention "I have been wearing a hearing aid and I'm happy with its high digital technology." Great, I'm happy for you! But why is that basis to assume no other child would want one, what about the other 25% of children who liked their CI?
You've now mentioned twice, that hearing aids are an alternative to CIs. The two technologies act completely differently and it isn't fair to propose that hearing aids be used instead, when they won't work in as many cases.
Also, I may not understand Eugenics as well as I think I do, but isn't this the exact opposite? We're not trying to hinder deaf people so as to remove their flawed genes from the gene pool; we are, in fact, trying to advance their state in life as best as we know how.
While I do believe in a person's right to choose (or being protected from having choices forced on them) I'm very torn about this issue.
Let's use vaccinations as an example. An infant is clearly in no position to make a decision regarding whether or not to be vaccinated, and yet, without those vaccinations they may catch certain diseases that may have lasting effects (back when it was still around, Polio.) Obviously we can't know what their decision might have been, but we assume that they'd want to walk, because we would want to.
Now CIs are obviously not a life threatening condition, and they can always be put in at a later date, when the person is capable of making their own choice regarding the issue. My only qualm comes from the issue of acclimation. The longer a person has time to acclimate to a CI the better their results, or so I've been told. If a person can only ever remember hearing the noises a CI generates, they can more effectively respond to them, whereas a person who has lived in silence for 18 years would have a much harder time adjusting. There was a case study (I wish I could find it, somebody help me out) of a man who was blind for the majority of his life. Then (I can't remember if it was just a "miracle" or whether he had some special procedure) sight was restored to him. Unfortunately, "seeing" isn't just something you can do, it's something you have to learn how to do. Perceiving depth, making out distinct shapes, separating foreground from background, these are all things we learn to do as we grow. The same principal can be applied to all of our senses. We have to learn how to hear, how to recognize what a noise means, interpret where it came from, etc. If we can start a child learning how to do those things, why wouldn't we? Why would we assume that they can make any more of an informed consent when they're older, having never experienced sound? I like the way my PI describes informed consent to me, and I think it applies here, "I can do my best to explain what's going to happen, what I'm going to do, how it will affect you, and what might go wrong. That being said, it isn't reasonable for me to assume you actually know what I'm talking about unless you've gone through all the training and school I have. Informed consent isn't so much the patient choosing one thing over another, it's simply an acknowledgment that they don't know what's right, but they're willing to trust me to make that call." The parents aren't sure what their child might choose, how a CI might benefit or hinder them, but they're making the best call they can.
I don't think parents are wrong for wanting to be able to talk to their child, or to let them have a chance to hear the world around them (or vice versa.) I also believe, that parents are the authority in this area-while a child is too young to make decisions for themselves-NOT the government or doctors. But again, we don't know what their decision is, so I believe the assumption that a human being would want to hear rather than be deaf has to be made. I wonder if the same question would arise if instead of treating deafness, we were treating paralysis. Should one allow their child to be confined to a wheel chair for 12 odd years and then allow them to decide if they wanted to walk? Maybe a child should be blind until their 16th birthday and then have a choice to decide whether to see or not? When I ask myself these questions, I can't answer anything other than "Of course they'd want to walk/see, I'm human too, I can empathize with that situation." And it's that answer that makes me question why I have to think about this situation so carefully.
If it turns out that when the child is old enough they want to have the implant removed, or simply turned off, they should be free to do so. You can't provide them with a choice as an infant, but if you don't give them a CI, they won't have a "choice" when they're old enough. In order to make the best choice for themselves, they need to know both options. You can make a "choice" only knowing one option, but that's really more of coin toss than a mediated decision.