In China , they have alot of suku kaum with their own language like Hokkien / Cantonese and many more ..so to unite everybody and make one national language ..they use Mandarin ...

But in Malaysia , i dunno why they need to use Mandarin ? you are free to talk your native language which is Hokkien or Cantonese or any other .. bahasa perantaraan already have Malay Language for Malaysia ..so why need Mandarin ?