I would certainly try it, although I was never very good with putting decals on model airplanes as a kid so I don't know how well I would do.
Some people want them to stay in the original condition, some want to restore them to look original, some just want them clean and working.
A friend recently picked up a Featherweight in pretty rough shape, for $50, and was talking about painting it red; I'd never heard of that but she said people paint them all manner of colors.
Make the machine your own, color, decals, etc.