I learnedthat, in hindu/indian culture, the flute or flute-like instrument was the first instrument beyond the voice. The reason being that it was sort of an extention of the breath. As we know, the voice is quite a versatile and expressive instrument. I’ve played keys for 24 years. I’ve been playing melodica for only 6 months. I prefer the melodica. I don’t think the question should be whether it’s an expressive instrument, rather we should ask “what is the melodica best at expressing?” Different instruments express different things.