Well the issue with Choclear implants is they are completely optional, you won't get ill without them. Yet they still involve an operation. So bit of an ethical issue there.

A recent study also showed that they work much better if they are implanted at about age 1, rather than 5 or so as is usual now. No way a 1 year old can consent though.

And then you have the whole 'deaf community' thing. Don't know where that's going. A lot of people with deaf children though aren't deaf themselves, so there is less issue there.