Would you prefer 75°C with 29 dBA ? (educated guess)
I think it's that you weight it more because you're commencing testing from an extremely lofty point. Given you work from room "well below 20dBA ambient" background noise such a level is like "good recording studio" or exceptionally quiet.
In perspective 30dBA would be nice for like a bedroom at night "quite" in most suburbia towns (and no..., or snoring). Consider CPAP machines used for sleep apnea therapy are great if between 24-27dBA, and those most often sit on the nightstand next to your bed. That’s pretty low given most occupied spaces of a house might be like 35-40dBA during the day. Dropping 3dBA is a "whole perceptible level lower", so 29dBA would be boarding "faint" considering it an "open sided" case.
I suppose when you equate it to the MSI GTX 660 Gaming card you tested it feels worse, that had provided 63°C and 31dBA, and that's just plainly extraordinary. When scaling from that I see your opinion, but that’s almost too unique to use as a baseline. However this P-C is better than the EVGA GTX 760 SC w/ ACX Cooler, offering 72°C while 38dBA, which you do point out as "simply too noisy".
With most all having the card in a closed case, cuts noise even more, having the ability to be
full-on gaming… I’d consider 72°C while 33dBA still reasonable, that’s all. I judge the "best balance" for cards of this level being more in range like 70-72°C, while 31-33dBA fine.