Polio, smallbox and malaria are diseases that no-one wants to have.
There is no call to abort children who may have smallpox or polio at some stage in their life. There are also treatments or preventions available.
It's different.
There are around 8 million people with hearing loss in the country. In fact, most of us will have hearing loss by the time we die. Ever thought you don't want to be alive at the prospect of that? If not, why not? Because not hearing something does not cancel out all of life's goodness, all of life's joy.
The Archbishop of Canterbury is partially deaf!
'Not hearing' is not the end of the world. It makes life a challenge, yes, but the deaf community would have a fit of the vapours if they thought people were suggesting the planet would be better off without them.
As for blindness, try telling Professor John Hull that the planet needs less people like him around. 'Google' his work. Brilliant man. And has much to say about how society devalues those with a disability.
There are some 9 million people with disabilities in the UK. The vast majority of us lead lives that we cope with perfectly well, lives that have some challenges but which also have many blessings. From my disabilities, I have learned patience, I have learned the true value of friends, I have learned the beauty of life rather than materialism and 'Hello magazine' values, I have learned the wonder of nature, I have learned that all the money in all the world can't buy you happiness. I wouldn't swap those lessons and experiences for all the proverbial tea in China.
But I'd change people's attitudes, and make sure there's help for people if they need it.