basically just put pads anywhere on or all over the heatsink assembly to thermally connect it to the bottom plate to help dissapate heat. You could also try adding some between the heatsinks and unibody, but you'd need to remove the plastic duct things to do so which may require a lot of disassembly. I haven't tried it yet, but I think it will probably help with cooling a lot by exploiting the aluminum casing as a heatsink.
To be able to run mac os? Maybe they didn't even purchase it. The priority usually isn't to have a cold quiet machine but to make it perform as best it possibly can, as the processors throttle significantly as the cooling system can't dissapate enough heat. Suppose you have a macbook pro and you want to play an intensive game on it for one of many not uncommon reasons (in my case my father's macbook pro was the most powerful computer we had and I was able to use it while he had one supplied by work). It would throttle to keep the processor at 80 degrees and i'm sure some thermal mods would've help quite a bit. The entire case is made of aluminum, perfect for dissapating heat! But it's thermally isolated from the cpu heatsink so it doesn't fry your lap. But if you don't use it on your lap you would rather let it help cool your processor and get better performance.
Valid point of view,
Yes I have a Razer Chroma X + 5700 XT...