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

You'd be surprised. Mostly from what I've gathered, they discuss the cost of the acquisition of hearing -- at all -- as compared to their current condition. There are significant differences in how the brain processes sensory input from a profoundly deaf/blind/etc person as compared to a hearing/seeing/etc. Having even 50% hearing restored would 'cost' a deaf person the depth and richness of their other perceptions. It really can be boiled down to a question of net expected utility.

But then there are also those folks that stubbornly identify around the culture dedicated to the absence of a given sense and as such can be seen as something of a 'permanent victim' mentality -- at least, that is my perception.