The farther the pad is from the caliper pivot point, the less force you can cause the pad to apply to the rim, for the same hand grip force on the lever. However, the difference isn't huge - roughly proportional to the change in caliper pivot-to-brake pad distance. Most people have enough additional hand grip power available, some women and children might be the exception. For them, better pads and cleaner rims should mostly offset the larger brake reach. Also, adjusting the brake pads to run close to the rim will help.

It seems to me that if braking power was really a problem, some enterprising company (probably French) would have developed a brake caliper where the cable runs through a pulley (like a compound bow, or a block and tackle).