Why would some people in post civil war america hold this critical view of lincoln, the man we celebrate today for ending slavery

Lincoln was criticized most for his suspension of habeas corpus during the war allowing him to hold people unconstitutionally. Additionally he was criticized for using federal funds and war powers without a declaration of war. Lincoln viewing the war as a rebellion never asked for a formal declaration. Southerners would be most critical after the war being Lincoln helped to end slavery which will devast their main economic system.