Cross hatching helps "grind" the pads until they are exactly matched to the shape of the rotor - until they are "bedded in". When they are exactly matched, there is maximum surface area between pads and rotor, creating max friction, resulting in fastest braking / reduced stopping distance. It also eliminates the opportunity for the pads to vibrate against the rotor when applied, which would create noise. So, the cross hatching gives reduced stopping distance, at the cost of some pad life.

I used "reduced stopping distance" instead of "better braking", because IMHO distance is only one factor in "better". Most significant to me is minimizing heat build up, in the brake parts and in the fluid, because heat creates "fade"- the brakes become less effective each time you use them repeatedly in rapid succession. Cross drilling or slotting is one of the tools to aid cooling. I don't think this ever becomes a factor in legal-ish daily driving, even in the worst commute. It could become a factor on roads such as twisty mountains at high speed, and will when racing on a closed course. Other factors are "feel" - how well you can precisely apply just the right amount of braking, how progressively the braking is applied, and how well you get feedback through your foot.

I go into this, because it's my strong suspicion (true, a GUESS) that we are unlikely to reduce stopping distance much, even at considerable cost. We have light cars with large contact patches, and it's usually losing friction between tires and road that's more of a problem than between the pads and the rotors. We may well be able to reduce fade and improve feel. How important this is to each individual will indicate how much upgrades are worth to each driver. I'm already a bit worried about getting wacked from behind by a tailgater with less effective brakes, though it's still better to be able to do it.
'Course, I'm wrong about lots of things.