Yes, we agree on live acoustic music as reference. That is why I was talking about emulating realism.
Yet natural sound as the absence of distracting flaws, as David suggested, is problematic. If you don't want distracting flaws, the quickest way to get there is covering up the flaws, rather than addressing them head on.
When I upgraded my system more than two years ago with new amp and speaker system, it was immediately clear to me that realism had increased dramatically, in the sense of articulation, energy, tonal differentiation and resolution -- micro resolution of timbre, separation of instruments, overall clarity.
Yet over time it also became more and more clear that artifacts, distracting flaws, had increased as well, such as exaggerated hardness and a slightly metallic coloration of sound. The much more articulate and resolving nature of the new system had exposed more problems with my room acoustics, an issue that at that time I had already worked on for years, so I knew that it probably was still haunting me. Also, as it later turned out there was a mismatch between preamp and amp.
So even though realism had increased, at the same time the sound had in a sense also become less 'natural' due the greater prominence of artifacts. If I would have gone the 'natural' route, I might have opted to again go for a less 'offensive' sound, and sold off the new components. That, however, would have been a HUGE mistake.
Instead I chose to stick to the new level of realism that the new system provided and to work on reducing the artifacts, in the confidence that there was nothing inherently wrong with my gear choices, but that I had to work on the acoustic environment instead. Later the introduction of a preamp from the same manufacturer as of my amp finally let all the pieces fall together, eventually also aided by further improvements in speaker setup. The result was, BOTH in terms of realism AND naturalness (in the sense described), vastly better than before. The holistic sound experience is in my view also much better than before.
I let realism be my primary guide, and from that vantage point I was addressing remaining artifacts. Had I chosen a 'natural' sound, in terms of lack of distracting artifacts, as my primary guide instead, this would have been a grave mistake and the final result would not have been of the high and thoroughly engaging quality that I enjoy now.