Here's a revolutionary thought: The A5s and HD6s were designed to reproduce music as recorded within limits of cost and size. They weren't targeted to any genres at the expense of fidelity.
I'm not entirely sure that what you are saying is completely true, unless there is some information that clearly addresses those assertions. I do not think it is at all a stretch to imagine that at some point in the development of any piece of audio reproduction gear that engineers, evaluators, managers who need to sign off on a stage of development will play actual music through the devices as part of their evaluation work. That should not be a controversial assertion for me to make.
My point remains, classical music is such an irrelevant genre in terms of popularity (not in terms of validity as an art form) that to imagine it likely that anybody would really use that genre to tune/evaluate with, in any meaningful way, to me feels like a stretch. In particular desktop speakers that are mass market/consumer and affordable. Now if we we're talking large, expensive designed to fill a room speakers, I could see somebody saying hey, we need to run some classical or large scale ensemble music through these bad boys because reasonably, some of their target audience, however small a percentage, may actually listen to classical. I will take a risk and be wildly speculative and suggest that as the speakers get bigger and more designed for larger rooms, more expensive systems, that the percentage of users who actually listen to classical would go up. Simply speculation on my part of course.
Saying this, I will of course note that it is entirely possible that classical music may experience a, pardon the pun, renaissance, and rise in popularity. But even so, it would have to rise a very long way to become truly relevant in any commercial sense. Still, there are niches and gear is targeted to niches so somewhere I could imagine somebody designing speakers with classical music as their main evaluation genre. Why not?
I would also be quite a fool to not acknowledge that I agree with your general point that it would be bad business to design a speaker or headphone to excel at only one genre at the expense of general reproductive fidelity. That was never my point. As terrible as this admission will sound, I will be honest and say that I forget what even started this line of conversation and I don't feel compelled to go back and read the thread again. Very lazy on my part for sure.