You are a Canadian and trying to stir things up with this?
Wars over man, Lincoln dropped the big one.
Power and control.
I think many Northerners were afraid to free the slaves for the same reason the Southerners feared it, a large, culturally alien group with few skills and some unknown percentage racially resentful moving into their communities. There were definitely powerful people who were abolitionists in the North however.
As far as Lincoln is concerned, which is a separate question, is whether he, himself wanted to free the slaves in the first place. I don’t believe so. But in the process of doing so after the death of over 600,000 Americans, he did the very moral act of emancipated the slaves while at the same time committed the immoral act of betraying the Constitution. In fact, he routinely trampled on the Constitution by undermining States Rights, before and during the Civil War. As a result of this I believe we have ourselves slowly become slaves in part.