"Can someone tell me why it matters how things were done in the past?"

Because it is interesting in itself. That should be sufficient reason, but if you need more, then because it is a guide to what works, and continued to work for many generations. This form of the music continues to envelop the listeners who enjoy such. As for other forms tried out today or whenever, whether you call it adaption or development, this extends the form but does not necessarily replace it. The pop protest singers of the 60s and the folk-rock of the 70s extended folk music, but did not replace earlier forms. The good will be kept, the bad dropped, but the older forms will continue.