Rick - I'd like to take a stab at answering your question of "why does it matter?"
From a gun maker's viewpoint, there are definite advantages and disadvantages to every type of stain and finish. Many of these shortcomings can be dealt with, some must just be accepted. I have used and will continue to use your excellent finish - more specifically the sealer - but only for certain projects where it's use has merit. Some guns are going to require something quite different. When building a gun, every aspect of the build needs to add to the desired final character of the piece, and for me not every gun wants the same finish. In this approach to building guns, the "project" is initially a blank canvas, and everything that goes into building it can be likened to a painter's palette.
There certainly are gun builders who use materials and methods to build their guns that are close or identical to the original materials and methods - use of wrought iron in place of modern steels, case hardening low carbon frizzens, forging various springs from simple carbon steels etc. - and this is done to closely emulate the old work based on the best available research. If an entire gun is made using the "old" methods and materials, use of an unsuitable finish would be out of the question.
No offense meant, but I am curious why you would think that if any of us saw a freshly made 18th century rifle we'd be less than impressed with the color and finish? There's a lot of us here who would trade our firstborn for that kind of opportunity. I'd say you are correct about the years of handling etc. contributing to the current appearance of most of our old originals, but a lot of us spend countless hours studying, experimenting and comparing notes with one another to try and bring it all back to life - or at the very least add more colors to the palette - and as a result we probably have a better than fair guess as to what a brand new one looked like.
