Well I don't know about orchestras playing out of tune, I never honestly heard a bad one. It is interesting having the music being played live, but recorded individually.
During a live concert the distortion created by the environment cancels out eveything that is slightly out of tune. You are also much less prone to hear musicians mistakes. When you are recording this with high quality equipment this becomes much more obvious.
A good example of this is the annual Queen Elisabeth Contest here in Belgium, where the live audience can get very enthousiastic about a contestants performance while the TV and radio listeners go meh & vice versa.
Even rock music is mostly recorded seperately nowadays and mixed afterwards, unless the band wants to go for a lo-fi live sound.
