Regardless of the GPU temps being manageable, the cooler it runs the better it performs. I would rather have it automated based upon GPU card temps. But that requires me to manually turn case fans on maximum in order to dissipate the heat that the graphics card is dumping into the case. If I turn all my case fans on full throttle, and my 3 FTW fans on the card, controlled by EVGA Precision XOC on aggressive fans curves, then the card will not go over about 70c maximum. When I said even when the GPU is "burning up" I only meant relatively in comparison to the CPU. I have a good graphics card, arguably the best/most advanced one on the planet at this moment. My CPU has an efficient cooling system with an Arctic Liquid Freezer 240. Of course, all this will be different from person to person and all spends upon the cooling systems used in their computer for their CPU and GPU.
If I simply make a more aggressive fan curve based upon CPU temp, which sounds like you are suggesting, then my computer will be a jet engine/glorified air filter even while surfing the internet and having virtually no load or heat stress on the GPU. I do have all my fans dependent upon CPU temps, but since my CPU stay nice and cool even while my GPU is burning up, my case fans don't help cool the GPU since they aren't getting a signal concerning GPU temp. How much work the GPU performs is not related to how much the CPU performs, and is individual to each and every game or program being run as to how much it asks of the CPU or GPU at any given time.
There is no direct correlation between CPU and GPU workload and heat, and therefore why we/I need fan control based upon GPU temp as well and CPU temperature. It's the GPU that produces much more heat.
My CPU stays nice and cool betwen 30 to 60c even in heavy gaming sessions. Its not ideal but you can adjust the curve nicely. So mostly CPU and GPU are ramping up on gaming. You can set your fans on fan expert 4 to CPU temp and go from there.