I take it you've never heard of slotted rotors?
Of course ... but it is a different situation (and one with its own set of stress-concentration issues).
If you have a brake rotor with through holes or slots, the brake pad still sweeps the entire surface. Apply the brake hard, and (at least as a first-order approximation) the whole braking surface raises in temperature uniformly. Where there is a hole, there is no material to thermally lag behind - there's no heat generated but there's also no material present, so it all changes temperature (more or less) uniformly.
If you have a brake rotor with partial reliefs in the pad-swept area, that material is there (and represents thermal inertia) but it is not swept by the brake pad, so it won't immediately see the temperature rise from a hard brake application. The material that is there but not swept by the pad, will lag behind in temperature. So the material that is swept by the pad raises in temperature and tries to expand while the material that is not swept by the pad lags behind in temperature. This introduces thermal stresses in the material, not to mention the cut-down area is now thinner so the forces are imposed on a smaller area, i.e. raising unit stresses.
And obviously there are brake rotors out there, mostly for automotive applications, that have partially slotted surfaces, and there are the occasional OEM motorcycle brake rotors on older models with that feature. BUT. Those slots are much shallower relative to the (typically much thicker) thickness of the rotor, much narrower, and much smaller in number than what is being proposed here.
I am not saying the proposed brake rotors are going to fail. All I am saying is "be careful". Changing design features of a safety-related system has to be approached with considerable caution.
