Some states - yes. But even so it was still legal - had been (and still was in some places) practiced in Northern states, and protected under the Constitution. Being deprived of $4 BILLION illegally doesn't concern you? The north ratified the Constitution, yet failed to uphold their end of the bargain. Compensated emancipation (not paid for by Southerners - why pay yourself?) was a choice - not theft.
You say compensated emancipation was an option and I would ask how? Ending slavery in any way, shape, or form would have required a Constitutional Amendment. I think that we can both agree on that. With 15 slave states that would mean that you would most likely have had at least 30 votes in the Senate against any amendment ending slavery. THere is no way that any such amendment would have gotten the necessary 2/3rds votes it needed. And that would have been against ending slavery under any conditions, compensated or otherwise, because the slave states saw no reason to end it. Why should they? Plantation agriculture was the source of their prosperity and that industry was fueled by slave labor. So a Constitutional resolution was out of the question.
So the south went to war. And once the war was ongoing then what use was a compensated emancipation plan? Even though Lincoln proposed it on more that one occasion as a chance to bring southern states back into the Union it never had a chance to succeed. The southern states were not about to drop their rebellion and rejoin the Union. And then after the Emancipation Proclemation who would he have compensated? All slaves in the areas in rebellion were immediately free, at least legally. Why compensate for someone that was already free.
So I would be interested in your view of how your compensated emancipation plan would have worked?