My recent experience say yes! Right up there with how well it can be used. Satisfaction is paramount and if you can't satisfy the requirement then you is screwed. The right size is critical for satisfying functionality.
So where does my robot stand? When it is finally printed and strung together it should be able to stand 23 cm tall. Barbie is 29 cm (5'9" really?). Apart from being intimidated by that Amazon Wonder Woman, I think my robot will work well. If it was printed any smaller I think there would be big problems with joint strength and the size of the internal tunnels for threading the elastic. But how big is 23 cm? Here are some images to go on with while you wait for the final result.