I'm a big fan of Floyd Toole so my disagreeing with some of his conclusions doesn't mean I don't respect his other work. As far as I know Floyd is not a recording engineer, and he hasn't mixed music professionally if at all. So that could be a factor in his opinions. His statements about early reflections defy my own personal experience, and the experience of almost every other audio engineer I know.
I know about Floyd Toole's tests showing "most people" prefer reflections. I also have his most recent book and many of his AES articles. But I have questions about his research that could affect its value. For example, how large (wide) was the room he used for those tests? Of the people he tested, how many were experienced listeners and how many were ordinary people with no particular interest in audio and music? I know that one of his tests had a group of mastering and mixing engineers listen blind, and the results were mixed with some preferring reflections and others not. But what I read didn't say where the various people were in the room. If the people who preferred no reflections were closer to the center of the room while listening, and those who preferred reflections were closer to the side walls, that would certainly skew the results. Learning to appreciate good sound can take a few days or weeks. So if you parade a bunch of "non-enthusiasts" into a room and compare absorbers versus bare walls, I'm not surprised that some or even most prefer the sound of reflections.
I also disagree that side-wall reflections should be "neutral" due to loudspeakers having a flat off-axis response. If the reflections coming off a wall have the same flat response as the direct sound, the comb filtering will be most severe. As I showed in my
Early Reflections article the peaks will be up to 6 dB and the nulls will be very deep. But if the loudspeakers have a limited off-axis response such that the wall reflections contain less high frequencies, the comb filtering in that upper "clarity" range will be less severe. This is basic math. I have a spreadsheet that calculates peak and null amounts based on dB reflectivity, and I'm glad to share it with anyone who PMs me their email address.
I hope this doesn't come off as condescending: I'm convinced that recording and mixing engineers have better "learned hearing acuity" than most people, and better engineers probably have more refined taste. Of course, taste is also subjective so this is just my opinion. When mixing music you need to hear everything as clearly as possible. If what you hear is obscured by reflections and other room anomalies, mixes you think sound good will not sound so good later, or in the car or through other systems. One reason is that moving your head even two or three inches changes the tonality, compared to mixing in a reflection-free zone where imaging and frequency response are far more stable.
Over time mix engineers learn to appreciate things that affect clarity, and avoiding early reflections is one of those. Note well: Mixing in a reflection-free zone lets you hear much smaller changes in applied reverb and midrange EQ. Even at my age (67 in 2015) I can easily hear changes of half a dB or less in reverb levels and midrange EQ through both of my music systems.
Related, I played the guitar professionally for many years, but a few months after I started playing the cello 20 years ago I realized my sense of fine pitch discrimination had improved. Now, if a note is even 5 cents off it bothers me. Compared to the public who votes for contestants on American Idol who are horribly out of tune.
So I don't mean to sound elitist, but I'm convinced that people who prefer the sound of early reflections in a smallish room would probably change their opinion if they were exposed to better listening environments. Sometimes it takes longer exposure for the improvement to be obvious, so maybe some people might not immediately notice. But most people should be able to learn to appreciate the improved sound over a week or two after adding reflection absorbers.
I mention "professional" listeners only because I believe they have a more refined sense of clarity, and can more readily identify when something sounds "better" versus merely different. But I absolutely believe that most people can appreciate the improved sound quality from avoiding early reflections. Or they can at least learn to appreciate it.