Why did grant want to take Richmond?

Despite the tremendous goal of President Lincoln to capture the Confederate capital of Richmond, there was never any real danger of this happening until late in the War.

Early in the war, in 1862 General George McClellan, leader of the Union's Army of the Potomac, failed to even attack Richmond due to bad planning and the great generalship of the South.

It seemed that the only way to take Richmond in 1864 under Grant was to lay siege on Richmond.

Richmond endured a 10 month siege before it was captured. This seems almost impossible to believe that Richmond did not fall to the Union at the onset of the war. Such was the state of the Union's inept strategies and tactics.