Cyclo-Cross racing is my "why".

The traditional: Dismount, shoulder, run, drop & re-mount is executed from the NDS and requires a Front/Right lever.
Try the opposite configuration on wet/loose terrain to get "why" when a "whack" in the head results instead of an easily controlled rear slide on the dis-mount.
All of my machines are so configured for consistency in an emergency or when dead-dog tired.

That it's the same set-up on my motorcycles for the last 40 years is a plus, a well trained automatic & appropriate control response is a Good Thing.

As always, suit yourself.

-Bandera