That being said, within a year of using Windows 10 four (!) of my hard drives have begun making loud screeching sounds. They're technically fine, but still unusable.
It's really pretty nice in theory. The reality is that some components still emit a good bit of noise, and unlike fans, the noise they tend to emit isn't very pleasant. Power-hungry graphics cards are by far some of the worst offenders; without being masked by fan noise, they can be incredibly loud and irritating. An open bench PC is definitely cool, but was kind of a mistake in my case.
Fan tech has improved to the point that I think, more often than not, you really want to have them. Otherwise it's time spent trying to eliminate other noise sources that would otherwise be conveniently and usually pleasantly masked by a little wooshing.