不同基礎不同狀態的鋼琴需要不同的「音準」；不同風格的音樂需要不同的「音準」；不同的用戶（使用者）也許要不同的「音準」。

yes, you 're correct,
intonation is the most important things for a musician
even a professional musician.............
or a youth musician, intonation is one find of music perform....
if your tone is flat or shap, what will the audiences think? Bad performs? lack of practising or even not good at technique! it's amazed that if your intonation is bad,
you will find that when you grow up(music) , intonation is one of your life routine...
^^

although i don't know what's your question is, but i could share some of my ideas with you:

i agree with you, but in order to fit the marketing and many other factors, there are only few types of piano. everyone have different needs, so they would choose the thing that is good for them, depends on their needs