Once you have abolished slavery you have essentially made people literally worthless, the rise of genocide and the liquidation of millions following the abolishment of slavery is no accident.

Better that one child is sold then the whole family dies because of famine but that would be immoral wouldn't it.

Is it more moral for a women to sleep with just one man than the whole town I think so and I could think of a few women that would be more moral as slaves.

If there is more benefit in something than harm Allah has made it lawful for mankind Alhamdulillah