I don't agree. The body needs to be conditioned to cope, that's all. It doesn't carry anything unless you have a pack on your back.
In fact it's quite the reverse. You and the mind direct the body. Without you and the mind conditioned you cannot do Aikido.
It's like saying a car improves you. The car does nothing without you driving it. The car is maintained. The rest is nothing to do with the car. Purely down to you knowing how to drive.
I do aikido despite my body being out of commission and my mind like a bag of spanners.Cheers, joe