If you want to organise your music how you want, why were you using iTunes in the first place - an app which organises your music for you? Surely it was already not suitable for your particular workflow and never aimed or claimed to be?
How do you figure? Itunes is completely unaware of most qualities of music, in fact nearly everything unattested in metadata.
This is optional, there's a "let iTunes manage my music for me" checkbox somewhere.