If the disks were without those holes, you would strip your wheel spokes and frequency of locking your rear or flying over bike's bars when braking front would increase. Holes in the disk also aid in heat dissipation. The design, including the disk size is a balance of compromises all around.

There is only so much stopping power you can have, given the 'flimsy' wheel spokes (cars have solid cast fins connecting hubs to rims) and tiny tire friction surface with the road. Possibly the spokes, not tires are the weakest obstacle in the stopping power you can be given to your disposal.

If I recall, Shimano rotors are aluminum with a steel layer for the braking surface, which is why they bend fairly easily, but are pretty light in weight, not to mention the small air scoops they have to aid in cooling. I want to say that SRAM are steel, which is why their design is different for weight considerations and less bulky looking

Shimano rotors are either all steel (e.g. RT66) or Al/steel composite (e.g. MT800).

Yea I was thinking about the upper end stuff, with the Ice Tech

I am wondering if perhaps the temperature of your brakes is within spec, but your ability to resist touching them is not

It's not so dramatic as that. If the outer diameter were a continuous circle there would be a bit of brake pad that never got scraped by a cutout. Even the most prosaic rotors have a notch opposite the end of every arm. They also have a hole in the end of the arm opposing the notch to do the same thing at the inner edge of the pad.

This is the plainest example of a bike rotor I can find right now... still has cutouts

https://cimg5.ibsrv.net/gimg/bikefor...0fc99d0f54.png

It’s the forbidden fruit. If I touch it, it’s going to burn, so I must touch it.

When my wife hands me something from the fridge and tells me to smell it, somehow, I can resist that.

https://cimg5.ibsrv.net/gimg/bikefor...56bde45ef2.jpg
Composite