Saying that nothing has changed, to me, is like saying that a new turboprop business aircraft is the same as an early 20th century monoplane because they both have propellers and the same design of aileron and rudder.
I or no one else is arguing that
nothing has changed. To me as a gun enthusiast I feel the advances are significant, and are certainly enough to keep me lusting after many new things I see. However I doubt we're in the majority.
I am arguing that from the standpoint of the average non-gun-nut consumer, things haven't changed
enough. For Joe or Jane six-pack who wants a .38 for his nightstand, a J-frame blued steel .38 he may have inherited from his grandfather is not demonstrably different enough for him to go look up a new stainless Ruger SP-101, a S&W Scandium/Aluminum snubbie, or a Taurus with it's "Ribber" grips. Same thing if it was an old 1911, he'll look in the case and see prices of $500 up into the thousands for 1911's that don't look much different than his "free" one, or the one he bought 20 years ago, and will shoot the same .45 ACP from Wally-World's sporting goods counter.
Similar arguments for Joe deer-hunter and his grandfather's .30-'06 Model 70.
Guns last a long time. Markets reach saturation. Common mainstream calibers haven't changed much in the bulk of the past century, or fifty years, and all the really fundamental changes like caseless ammunition or electronic ignition primers haven't caught on. Man-portable ray guns, rail-guns, or coil-guns the same size or cost of chemical/kinetic firearms are nowhere to be seen.
For the sake of argument, assume that wear from daily use wasn't a factor. I know you drive a car every day, but don't necessarily shoot your gun (lucky dog if you do...). So here's an analogy: If cars didn't rust, or wore out at the average rate even neglected firearms do, and barring artificial external pressures like emissions laws, how many cars from the 50's, 60's, 70's, and 80's would still be on the road today despite all the advances?