The extra bits mean you can change how you filter the sound later, depending on what range your headphones/speakers are capable of reproducing without distortio

The extra bits mean you can change how you filter the sound later, depending on what range your headphones/speakers are capable of reproducing without distortion, or what your ears are capable of hearing. Who knows, maybe technology or genetic changes will allow future humans to hear in a wider range than we do now. Those people might appreciate being able to hear what our music really sounded like.