it's for the sake of running my esc's near 100% throttle, as that actually keeps heat down compared to low throttle.
additionally, the kv rating of the motors is what dfetermined my battery choice, and the smaller inrunner motors were chosen such that i would not have to replicate and match flywheel balances for modded flywheels fitted over outrunner motors. the motors themselves have plenty of torque and the extra torque of outrunners was not neccesary. in addition, there's the fabrication of a custom FWC pair that would hold outrunners which i did not wish to do.
each application is different. my 9000kv motors spin at around 32k rpm for the first stage and 64k rpm on their final stage. additionally the servo i use is a HV servo, and 7.2v is the highest voltage it is rated for to provide good torque and speed of actuation.
i designed and calculated around the overall match of the sysem's components servo, which led to the motor/ESC/servo/battery selections