I’m actually going to see a guitarist who might have a singer/melodica player accompanying him next week! I accidentally caught them rehearsing in the same building as the electronics group I participate in. The melodica player sounded fantastic. Hopefully I can ask some questions :D.
However, in my experience most people in Japan don’t take them seriously either. Same thing goes with the recorder- they are both seen as educational tools rather than serious instruments. Just about everyone has one though!
I agree though- “keyboard harmonica” does present an immediate image whereas melodica/pianica/melodion don’t.