You know why tuners drill & slot rotors? Because drilled/slotted perceived as 'performance', 'upgrade' and 'sport', just like red (or yellow) calipers, stripes, stickers and huge spoilers. Between solid rotors & unpainted calipers and cool looking brake kit - which one majority would choose and will be more willing to spend $$$? Exactly.

Think about it: what is better, more or less friction surface? And why they use slicks - if allowed - on dry pavement?