Although I prefer original bikes, I would also say there's good patina and bad patina.
For a fine old racing bike, sun-faded paint, rock chips, light oxidation from sweat and weather, cable rub, strap-wear, scratches on stays and fork from fast wheel changes, and even a small bar-slap ding in the top tube, are all fine. The bike was used as intended and reflects it well. Wax it and leave it alone.
But for the same bike that fell into uncaring hands for a period of time, sporting chewed up seat collar ears, big scratches from a chain-lock wrapped around its tubes, oxidation from being left outdoors, flattened stays from a bolt-on kickstand, and the decals torn-off from where the Goodwill used packing tape to attach the $9.95 price tag, holds only the patina of abuse. In these cases I think you owe it the bike to take it down the bare frame and lovingly start over. Yes, the "soul" of the wino that rode it around with the bars flipped up is now gone. Big deal, start giving it new "soul".
My thoughts on riding original/restored bikes differs a little from what I have read so far. To me the bike in the first scenario above is actually less enjoyable to ride. My attitude being, "it has made it this far and still looks great why risk a possible crash, or just more natural wear". Where as the fully restored bike to me is just like walking into a bike shop in 1970-whatever and picking out a new bike. It's a clean slate to be ridden as it would have been ridden in its day. Any major mishaps and just send it back to the painter and get back another "new" bike. The only risk involved is money. Which unlike old bikes they do make more of every year. Ride that restored bike right and in twenty years it will have the nice "original" look! But that's another can o' worms to chomp on.
Cheers, Jon Williams
Grants Pass OR