^^^ Yep! I was thinking bearing wear as well, and fans and CPU fan solutions are not too expensive. Neither are they difficult to install; if you can install a PSU, you can install fans and apply thermal paste
As for this being a common complaint... I had a noisy fan issue with my HTPC build, but that was because I didn't tape a wire out of the way, so the fan was hacking it! Since that fix, silence is the rule... I would suggest that a noisy high-end PC may be the result of a little sloppy building or parts that need to be returned. I am not trying to suggest anyone is incompetent, just that new parts should work "newly". If they are not, I think you should get troubleshooting - could be vibration from a loose MB screw, or you might need some rubber bumpers here or there, or this wire over here might need a little guidance.... it is better to not assume that that is simply the way things are and instead look for solutions.
In my opinion.