What do you mean by "unnatural"?
This is Amir's Predicted In-doom Response.
This is Stereophile's actual listening window plot:
Magnepan LRS, anechoic response on mid-panel tweeter axis at 50",
averaged across 30° horizontal window and corrected for microphone response,
with the nearfield panel response plotted below 300Hz. (
source)
If you chop 6dB off the 75Hz region (an artifact caused by the nearfiled measurement) the response becomes a lot flatter below 350Hz and down to perhaps 60Hz.
Having seen hundreds of JA's measurements I am inclined to believe that his is a much more accurate illustration of reality than the Klippel's.
In other words, Klippel don't do dipoles well (enough).
Bad (direct) sound is not just tonal balance issues; it's also distortions.
Indeed.
As Toole says "Humans have spent enough time indoors/incave to feel it's unnatural if indoors and hearing sound without wall reflections".
In other words, biased. So much so that many people actually enjoy room-generated distortion resulting from boundary reflection above the transiton range even though some of those are happy with treating the room or using digital correction below that...
"Preference" is a lot more complicated than we're made to believe. Taste - everyone's got one.