Oh, by-the-way, and I also owned a Colt Walker and several other percussion Colt revolvers, before i switched to collecting Winchester rifles. I also identified and authenticated the 21st surviving Fluck Colt Dragoon in existence, with the double Walker holster rig and Walker flask for a friend. . . who had it GIVEN to him by an acquaintance at a shooting range. Value at that time was somewhere north of $40,000! Fluck Dragoons were pre-1st Model Colt Dragoons made on Walker frames but with Dragoon trigger guards, and 1st model Dragoon barrels. They were in their own serial number range, and were, according to documentation researched by a collector named Fluck, made to replace approximately 225 Colt Walkers destroyed in service for the Texas Rangers. I was certified as an expert witness on antique firearms by the California Superior Courts.
No, my original Walker was not in shootable condition (don't believe those idiots on Pawn Stars who claim that an Antique firearms needs to be fireable to add value. I would NEVER recommend anyone shoot their fine antiques firearms! I cringed overtime I heard them say that or shoot one.) . . . I had a replica for that. It was fun to shoot. Clouds of white smoke!
Well, I would agree with you on the very rare, valuable, or interesting provenance items ("let's rip a few .45 ACP in that U.S. Army trials Luger to see if it works!").
However, on some items with delicate lock work (Colt Lightnings and Thunderers come to mind) functionality does indeed improve value. I like early S&W DA's, and their primary value is as shooters.