[Ron Wood]

Doug,
If you think about it a bit I believe you will "get it". There are several factors that make an item collectable. For Lugers they are primarily condition, rarity and historical significance.
Using your example, how much more valuable is a restored '55 Chevy with correct original colors, upholstery, matching serial numbers, etc., than one that really looks great but has none of the above.
One of the things that make this Luger desirable is its probable link to US military history. Restoration will make it look good again, but since there is quite some controversy surrounding Lugers that have all the characteristics of a US Test Trial weapon but do not fall in the hallowed 6100-7100 serial number range, a positive link, even one so small as a strategically positioned dent in the grip, is very significant to reinforce the probable historical significance of the piece and therefore just as important as using the correct trim on a '55 Chevy.
Beauty is more than skin deep, it needs character as well. It isn't just a matter of losing collector value, it is preserving what little bit of history we can.