If I understand you correctly, you make a new point after 119 posts to this thread:
A large majority of audiophile speaker designs are low efficiency because a large majority of audiophiles don’t like some of the sound characteristics of high efficiency speaker designs. Or, as you say, they think they don’t.
It’s certainly a type of sound quite a few audiophiles don’t warm to particularly, likely because of another type of sound they’re typically exposed to or, yes, they dismiss this segment of speakers out of hand/sans 1st hand experience. Or, they may simply not like the ones they heard, for whatever reason, which is perfectly fair.
Habitual use is important to stress here, I find. It’s a bit akin to the sonic difference between passive and active speakers perhaps; using the same speakers in one and the other configuration I find the former is generally the more euphonic sounding, softer, less clear, less resolved and less transiently "snappy"/more smeared. To some passive here is the more "musical" and warm variant and thus more pleasing, whereas to others active is the musically more honest, resolved, transparent and less bottlenecked presentation and therefore what they prefer. Below is an excerpts from a JBL K2 S9800 review that highlights a universal characteristic of horn-loaded, large-woofer speakers and their type of presentation:
Horn speakers are not to everyone’s taste, and while a number of visitors agreed that this speaker seems remarkably free from the vices normally attributed to the breed, some listeners might find it a little too ruthlessly revealing, preferring something rather more laid-back and restrained. While the K2 does have some aggressive tendencies when worked hard, taking no prisoners among poor-quality software, sources, or amps, its ability to "suck in" the listener and create involvement in even unfamiliar material is unparalleled in my experience.
One aspect of performance that’s somewhat different from the norm lies in the way this speaker interacts -- or rather doesn’t interact -- with the listening room. Most speakers have relatively wide dispersion in every direction, so that although the sound you hear is dominated by the direct sound from speaker to listener, it is richly augmented by room-reflected sound. However, both the K2’s large bass/mid driver and its mid/treble horns seem to have comparatively narrow dispersion through the midrange and treble, so there’s less room sound than is usually the case.
In that respect the K2 shows certain similarities to dipole panel loudspeakers such as the Quad ESL-988, which have a figure-eight-shaped distribution. This means that you hear more of the direct sound coming straight to you from the loudspeakers, and proportionally less sound reflected from the walls, floor, and ceiling than you would using a speaker with a much wider dispersion characteristic, such as the B&W Nautilus models.
Whereas the Nautilus 800 will tend to fill the room more, creating a strong impression that the musicians are actually sitting right there, the K2 and Quad provide more of an "open window" onto the recording sessions, revealing more of what the recording engineer intended, but less of the illusion that musicians are actually playing in front of you. This is neither praise nor criticism, as there’s neither right nor wrong here, but it is a relevant observation that has a significant impact upon the character of the listening experience.
This quality undoubtedly contributes to the very precise imaging, alongside this bulky speaker’s surprisingly good transparency. It’s not quite a match for the best dipole panels here, but is rather better than most box loudspeakers in this regard.
If that’s correct, I wonder how much the sound characteristics of the puny 10 watt often SET amps that are commonly used to drive high efficiency designs have got to do with it. Like some of the posters here, I certainly don’t like them. Would they sound different (better?) driven with a high current amp with a big power supply, even if the wick has to be turned a long way down? They would be under better control, particularly in the bass where most of the problem lies.
No, through high quality high efficiency speakers, not least very high eff. (i.e.: from ~100dB’s on up) all-horn speakers I find great quality SET’s to bring out the best in them. There’s a combination here of aliveness, vibrancy, uninhibited yet naturally warm presence and a lit-from-within sense of presentation that’s quite unique and utterly beguiling. To take full advantage of SET’s you need very high eff. speakers so only to use as little as possible of the few watts available, and stay in the very low range of distortion. By comparison some Solid State amps (less so SIT’s) with the same very high eff. speakers sounded somewhat grey-ish, a bit mechanical, less folded-out and just downright flat.
Myself I previously used a pair of very high eff. all-horn speakers, but for some reason I ended up not giving them the SET they deserved and instead veered more towards active with SS amps (30 watts pure Class A to the horns and Class D variants in the half kW range further low) and horn hybrid speakers that I use now. Again the passive vs. active sonic marker applies, though literally here; active with the horn hybrids I’m using now (~100 to 110dB’s sensitivity) infuses a vitality and ignited-ness, even with SS amps, that to me is akin to the sonic imprinting of SET’s + all-horns, the difference though being an added sense with the active config. of evermore ease, resolution and (a sense of) unlimited power delivery.