I will have to show Hohner the error of their ways!
In all seriousness, your observation about Hohner is right on.
At the same time, I misspoke in my post about making “professional” melodicas. I confused the word “professional” with “features.” The Hohner Piano 26/27/32-series melodicas (two pictured below) is a mid-quality melodica primarily made of plastic. Yet, the Piano 26/27/32 series is my favorite because these melodicas are so much more expressive than even the most expensive melodicas due to having true sound holes on the back and a propensity to bend the lower notes. So this suggests that a melodica does not have to be expensive to be good (at least to me). A similar melodica, with a few additional design features such as note bending enhancements, could be manufactured for the about the same cost as the Hohner Airboard.
So Hohner does not have to risk trying to build a $500 Soloist- or Hammond-quality melodica. They need to build interesting and expressive melodicas. If they do this, I think they would find a huge market of professionals and beginners who want to play a melodica, but find expressiveness lacking.
Make a melodica that approaches the expressive capability of a harp, and they will come by the millions as they have for the harmonica for a century or two.
I believe this will happen some day when someone in the industry sees the light. Maybe Suzuki or Yamaha will beat Hohner to the punch.