Are you suggesting that the research is flawed because it reflects badly on expensive products?
The targets you mentioned aren't drastically different to Harman and IEMs are usually slammed here for being way off the mark. A bunch of similar targets being similarly preferable doesn't negate that they're all a good basis for audio that will please most people.
Sure, there's more to audio than a target but we all know that. FR targets are the best objective guides we have right now. "Not good enough" implies a "better," which in this case doesn't exist.
No, the methodology is flawed because it compares too few targets, and this is a flaw that is very difficult to overcome. Lots of more expensive IEMs are tuned to the Harman target (EM10, Variations, Glacier, Xenns Top, IO Sogno/Volare, etc), so this has nothing to do with price.
I have been saying that "they are
all a good basis for what will please most people", and so the mindset of many in forum (that Harman is the only standard and that if an IEM is less similar to Harman than another, all else equal, it is worse) is inappropriate.
I actually don't think there is much more to audio (especially IEMs) other than FR at the eardrum. However, my opinion is that there are many FR targets that are appreciable and worthy of producing and listening to (or at least trying out). This is simply because not all the people have the "average anatomy" and "average taste"; the optimum for the entire population across music recordings might not be the optimum for a particular individual and the specific music that they listen to. Even for some one with the average anatomy and average taste, they might occasionally want to hear something that is different.
Also notice that Harman is actually the more "extreme" targets in the best bunch. It has the most 3k-8khz energy (IEMs that clearly try to tune to Harman usually have less of this region) and the least midbass energy (likewise, most IEMs that are tuned to Harman have slightly more midbass). It is very likely, not the dead-average among the best targets. Likely because of this, the Harman is at the moment quite polarizing outside of this community.