And be replaced with what?
And what of poor Southern whites who were share croppers and had no stake in the plantation system?
Sharecropping was not widespread until after the end of slavery. Small farmers in the South for the most part owned their own land.
While horrible a condition to be sure, it was in the interest of slave owners to keep slaves fed and alive at a minimum simply so as to work.
Well, yeah. You don't abuse or starve a valuable asset to death. Wouldn't make sense.
Slavery was immoral, an abomination before God and the ideals America was founded on. It had to end.
Except that virtually all Southerners didn't think slavery was immoral, didn't see it as an abomination before God or anyone else, and weren't in a hurry to see it end.