But is the ability to distinguish a discrete and limited number of tones that you have to learn to interpret properly to have any benefit from at all (even more so if the person in question was born deaf) worth an invasive medical procedure?

If the true objection was the invasiveness of the procedure, we wouldn't be having this discussion.

If cochlear implants cost €1, could be worn like earbuds and replicated normal human hearing perfectly, this wouldn't be an issue at all.

And I bet you it would be an issue. There are people out there who force female genital mutilation to their children -- that's an invasive procedure right there that is meant to deprive their children of an ability. And yet millions of people do it to their children.

It's not about the invasiveness of the procedure -- it's about cultures that choose to do evil in pursuit of their self-perpetuation.