Many many Hi level Brake manufactures make their top shelf kits w/ a 2 piece rotor design for a reason. The rotor will expand and contract w/ heat more effectively and evenly, the weight reduction alone is awesome compared to a one piece, the fact that you can keep the hats(which look 100x's better than a single/solid rotor design) and just replace the actual rotor disc is nice, they dissipate heat at a quicker rate than a solid one piece design will. There are perks to running a two piece design.
Brembo Brakes - GT-R Braking System
Project Mu Brakes - Brake Rotor - SCR Pro
Street Heavy Duty | Disc Brakes Australia
but if you don't trak, then I guess there is no point.