I know people with 44 yrs in who feel like they are starting over and are thrilled to pieces!!
They really are two sides of the same coin as you can use breath to project or absorb in yourself or in a connection with others. Without going into too much detail;
Consider what it means if your limbs are attached to your middle.
Consider what it means if you can manipulate your middle
Consider what it means if one of three ways you can significantly manipulate your middle is through breath.
If your training allows the ground to support the bottom of hara, and your arms are supported by top of hara, then consider that a body pressurized up and down (part of heaven/earth/ man means that anyone touching your hand...feels the ground, without you using isolated or localized muscle. There are quite a few tips and components to work in learning to do just that well and then a host of other things to add.
Breath is significant but not nearly enough to gaining a more complete grasp on aiki. Breath training for conditioning is fine, breath power and pressurization in use in freestyle...sometimes. The conditioning is what is important. Without proper conditioning "thinking" you are doing anything meaningful with your breath is a pipe dream. Then again, most people I have met in aiki arts don't even know; where their hara is, what their hara is, much less how to train to use it. What aikido mostly is...is using the hips and shoulders for power...a huge mistake. But worse if you don't even realize it and remain convinced you are using your center-hence modern Aikido.
To quote a song Your body is a wonderland.... with specific ways to train:
One-point is not enough
Connection is not enough
Breath power is not enough.
I got the impression that kokyu-ryoku
didn't just refer to "breath power". One translation I saw was "abdominal
breath power". In any case, do you think "kokyu" (not just breath) could be seen as IP while "connection" and the associated application of kokyu could be called "Aiki"?