I agree with post #54, & #55 for that matter. There is a happy medium between over-sensitivity, and excessive effort. The drawback of over-sensitivity is obvious. The main drawback of excessive effort would be fatigue over a long ride, leading to loss of braking power & potential vulnerability to sudden hazards requiring hard braking. Of course the coefficient of friction between the pads & the rims plays a large role in the trade-off between sensitivity and effort, so for any apples-to-apples comparison, that would have to be normalized.
Stiffness is quite another dimension to the problem. Boiled down, inadequate stiffness will show up as non-linearity, which could be manifested either as fade (******ing force flattens out with increasing force at the lever) or as runaway braking (control of braking is wrested from the rider, brakes lock up autonomously). Either way, inadequate stiffness can be very bad.