I always found it funny how Lincoln was portrayed as almost sort of a proto civil rights activist when he literally wanted to ship blacks back to Africa at one point and also said this in an 1858 debate with Stephen Douglas:
teachingamericanhistory.org
He somewhat softened his opinions in later years, especially after discussions with black leaders who turned out not to be subhuman apes.
Also the original shipping blacks to Liberia concept was one he was trying to sell to black people themselves as the best solution for everyone involved, and he invited leaders to the White House to see if they could work something out. So it wasn't a matter of rounding them up forcibly with no input and shipping them back to Africa in rickety, leaking slave ships.
(Ironically, many of the blacks who took up the offer and went to Liberia ended up at the top of society there and reinstituted what virtually amounted to the American plantations they'd been freed of.)
Lincoln wasn't an abolitionist, he was a pragmatist whose goal was preserving the Union at all costs:
"If there be those who would not save the Union unless they could at the same time destroy slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone, I would also do that."
Letter to Horace Greeley, August 22, 1862
Also note that this was a letter meant for publication at a time a war Lincoln was heavily lobbying to the public (and which was highly unpopular), was not going well at all, and he couldn't afford to look like a wild-eyed John Brown style abolitionist (not that he was one). This was before Gettysburg and other victories decisively turned the course of the War and its outcome was still uncertain and even subject to mass civil unrest resisting the drafts and otherwise criticizing the war effort.
The opinion of many of the average men getting drafted (while a rich man could just have his daddy buy him out of the draft) was I'm not going to war with my Southern brothers to free a bunch of niggers just so they can come up here and take my job. It was that simple. And Lincoln couldn't be perceived (even more) as essentially doing just that.
Even the vaunted Emancipation Proclamation was essentially Lincoln destroying much of Southern wealth with the stroke of a pen, just as Sherman in his March to the South destroyed their physical wealth. Whatever the opinion of the morality of slavery is (though I think history has been pretty conclusive on it), the EP was an instrument of war, not taken for its own moral value but for its damage to a wartime enemy.