Why can I not manage music that I own?

I *HATE* the music app. I want to manually manage my music that *I OWN*. I don't want to pay extra money to apple to sync my music in their cloud. I just want to be able to have a library on my computer and manage which songs and albums I put onto my phone. Why does Apple dictate that I cannot do this? Can anyone find a way to manage their own music?