yes it can help it cool, but rotors are designed to dissipate heat which takes mass. if you have a stock sized rotor and cut away material you know have less mass and less heat can dissipate which leads to warping and cracking.

i also remembering reading that crossdrilling was done back in the 1950s to cure a problem related to asbestos in the pad material in racing applications. asbestos is not used anymore, but people like the look.

now if you willing to spend $2,000 on a big brake upgrade that's a whole different ball game. those rotors were designed to be like that and can handle the heat.