Modern brake shift levers work best using one finger for shifting and two fingers for braking, pretty much like shift buttons and brake levers on hybrids and mountain bikes. When you ride on the hoods, the index fingers are resting on the break levers. While you can grab a whole fist of brake lever from the drops, if you actually tried to do this for real, you are going down as this is not how anyone ordinarily uses brakes on a road bike. For those with really small or weak hands, there is always the option of installing an extra set of break levers on the tops.