The idea that you can improve a tune by adding accompaniment is perfectly ridiculous. And pompous to boot. Arrogant even. You can embellish, surround it with harmony, make an arrangement with the tune embedded... but you can't "improve" the tune. You might well come up with something very agreeable. I love all my old Planxty and Bothy Band stuff. But you can't improve a tune. Unless you change the tune, and even then you probably won't be improving it. Bach wrote six lots of tunes for unaccompanied cello, and a good few more for unaccompanied fiddle. I'd love to witness some of these tune-improving strummers having a go at "improving" 'em!