Because wage slavery is ultimately not much better than slavery, and its abolishment does not necessitate the collapse of society. A world where no one is forced to work is a better world.
Wage slavery is just fine as long as I can feed myself. Time has proven that the fantasy that we will all kick back and let the machines do all of our work is a fallacy.
You won't love them less, but they will grow up in a world where they are not necessary. They will struggle to feed themselves, and the value of their effort will be low. They will be relegated to mundane, highly simplified tasks. Economics are cruel.