My brother will be 30 years old in August. When he was 9, he got a CI. It was sold as "now you'll hear." Chances are all the caveats were detailed, but parents and young children are wont to overlook those when new technology promises a chance for a big life change.
He used it for three years, working hard to make it work, to learn speech, and ulitmately he said it just didn't work for him. A honk of a car horn and a knock at the door sounded the same. And, he hated hearing.
I'll quote from something he wrote in college about it:
"I had gotten so used to my world of silence that I hated to hear sounds! Yes, you read that right. I have heard, and I hated it. The sound was just plain annoying. I couldn't get rid of it. Finally, in frustration, I took off the machine, dumped it into some drawer that I can't find today, and never looked back. And you know what? I'm glad I did! Let's say that tomorrow you suddenly wake up with the power of telepathy. You can read others' minds. At first you'd probably think "hey, cool!" but eventually you would face a problem. You can't stop this onslaught of other people's thoughts. You're *always* reading others' minds, even when you don't want to. You continually have to "hear" this, all the time. It never stops. You can't filter out any thoughts, unlike a person trained in telepathy would be able to, because you have never been able to do this before, and you don't know how to stop. How long before you go cuckoo? I'll be honest. If I woke up tomorrow, and I could hear, and I couldn't turn off this sense, I seriously doubt I'd last a year."
Now, he had the surgery over 20 years ago, and CIs have changed. Perhaps today they're better at adjusting it then they were then. I don't know. I know I've heard what an unadjusted or poorly adjusted CI sounds like, and I'd toss it out too.
While I'm sure that since the CI wasn't what my brother expected caused some of the disappointment, he DID try to make it work for 3 very frustrating years. But ultimately he realized he didn't need to be fixed, he liked not hearing, and was fine the way he was. Sure, there are some hurdles... but I think it helps that he doesn't consider himself a deaf person. He consideres himself a person... who happens to be deaf. I.E. an individual.
That's the point... CIs will work for some, not others. Oralism works for some, not others. ASL works for some, not others. Everyone is different, everyone is an individual, and everyone has different strengths and weaknesses. That's nothing unique to the deaf community--that's just S.O.P. for the human race.