Two of the useful features of this setup (I have no evidence to prove they were the design reasons) are:
- when braking in a hurry stamping down until you reach the bottom will leave you in first, NOT neutral. This is much safer in many respects than being left with no power in an emergency situation.
- when starting from neutral, there is no risk of ending up in the wrong gear; 1 kick down leaves you in first gear. I have ridden very old bikes where neutral was the bottom gear, and sometimes the first click up would leave me in second - where I would stall, not being prepared for this.
I have also ridden a bike where the gears were the other way round, with 1st at the top, then neutral, then 2nd, 3rd etc - kicking down to change up a gear...less natural...very odd when accelerating hard