The simple fact is that joysticks are less precise. Its possible to move a mouse at any speed, at any time, in any direction much more quickly and accurately. Simply put, nothing beats the precision of the mouse in view movement.
If you wanna get technical its probably because mice have a flat surface and move linearly over them, movement of the mouse corresponds directly into world movements. With console joysticks the movement speed is based upon the joystick position, which means that you can not simply move the cursor you have to "speed" the cursor to the position you need.
I admit that keyboards arent the greatest but hey, you have a hundred keys to press. Surely you can find a suitable layout with that many