Industrialization killed slavery not morality.

The reason for abolishing slavery was that it was a backwards system that prevented the super exploitation that came naturally for the proletariat.

The abolition of slavery was the proletarization of slaves. It absolutely was economic in nature. There was no economic need for slavery anymore, it didnt end racism tho, which was the ideological weapon that permited slavery.

Racism was simply repurposed for the black (and other) proletariat.

Industrialization killed slavery not morality.

Where is the goodness?

You have an idealist conception of history.

How would this allow superexploitation?

When capitalism becomes more productive than the market can handle it just shuts down the factories or when it gets more efficient it just gets rid of workers. Try doing that with slaves.

Proletarization created a pool of unemployed and a labor makret that benefited capitalists.