I don't know what kind of income level are you talking about when you say "middle class family". Afaik, most middle-class families can't afford to spend money on a good quality grand piano. I would be even surprised if they even had enough money to maintain it or if they had enough space for it

It's gonna be hard to tell some parents why they should dump over $1k on some fancy piano when they can spend way less than that on a digital piano.