I really don't want to get into a sound quality debate, but in 18th century the sound quality was not that great. Nobody knew about dynamic ranges and whatnot, and composers were mostly imagining how their music would sound like. Now, my opinion is that classical music produced today is idealized, inadvertently sliding it away from its original, intended sound. Same goes for Jazz and 30s music, for example, same goes for rock-n-roll and well, pretty much everything produced before the 90s.
Some people strive to get "best quality" but by that (personal opinion here) they don't realize they lose exactly the core of the music. Good music from the past needs imperfection. It's not specific to music; there are color HD versions of Laurel and Hardy, some remasters use various XXI century techniques to remove shaking and blurring inherent to original recordings, and then you end up with artificiality. You gain clarity but lose immersion.
For some, "purity" must equal "cleaned up". To me, it's "the way it was". YMMV.