Why game sprites are coloured in the computer instead of colouring them outside and scanning them in.

Why game sprites are coloured in the computer instead of colouring them outside and scanning them in.

I just had a thought today. I usually see video games where it appears that the creators used a graphics program like MS Paint to colour the sprites (for example games like King of Fighters, Kingdom Hearts Chain of Memories). I wondered why they couldn't just colour those sprites with their hands to make them look nicer and richer. I still don't have the answer.

But I have realized that with graphics programs the image filesizes are smaller because fewer colours are used. You just flood-fill an area with a uniform colour. Whereas if you coloured it on paper before scanning it into computer, there would be multiple colours(or shades of colour) on the image due to the rough way the hand coloured the picture. And if you tried to reduce the colour depth of the image to reduce filesize, it might end up looking uglier than an image coloured with a graphics software