Some bikes have quite a big gap between 1st and 2nd, I should imagine for gymkhana this could be irksome, over revving in 1st or under revving after the up shift. Lowering the gearing would give more flexibility in 2nd & fewer gear changes.
I've geared down pretty much every bike I've owned. For some reason the open road speed limit does not match the engines happy place. On the TDM with standard gearing 100kmh in top was about 3700 rpm, just under that happy place & lacking responsiveness when i opened the throttle. One tooth less on the front & it sits at 4000rpm but has significantly more torque available when i roll on or for hills & strong head winds. Makes the bike nicer (& lazier) to ride.