First, from a safety and functionality perspective, there is no excuse for poor workmanship. This really isn't the crux of the debate, however. What's being questioned are the merits of different aesthetic approaches.
A second point I don't think can be debated... Levels of finish and how fine work was completed in the period depended on many factors including where it was produced, when it was produced, the skill of the builder, the perceived value of the object etc. It follows that there were different standards or workmanshiop (fit, finish) during the time in question. For example a Twigg fowler was finished different than an English trade gun, or a John Armstrong rifle, was generally finished to a different degree than an Appalachian mountain rifle. I'm not refering to mistakes, but a commonly accepted level of finish given the above criterea. So if approaching building today, from a purely historical perspective, a variety of finish levels would be appropriate depending on the project. In fact, I would say that given this approach, overfinishing a gun today, may make it less representative of what is being emulated. The opposite could be true as well.
Putting saftey, functionality and historical correctness aside, it comes down to aesthetics and what people find appealing. This is a purely subjective decision. To say that individuals are wrong for having certain likes makes no sense at all. There is no right or wrong. This is a slippery slope and it's not uncommon for some who might be on the outside to attack the commonly held beliefs of what is valuable or has merit. Not a good tact to take in my view.
If people disagree with this assesment, that's fine, but please try to addres what about my above arguement is not valid. These sorts of discussions can explode into tirades, but oftentimes little is really said.
Jim