The humiliation in the Crimean War showed the need for action.
Dmitry Milyutin was Minister for War and he believed that only a free population would make Russia’s army capable of improvement.
Alexander II had liberal ideas and believed emancipation was the right thing to do.
Economically, it made sense as free peasants would have more motivation to work hard and their hard work would produce a grain harvest that would generate money for the state.
Freedom of movement was required for industrialisation to take place as serfs were needed to move to towns and work in factors if they were to be built.