Thought I replied to this, twice. Maybe another thread? Well, third time's a charm.
There's two or three sides to the decline in "traditional" muzzle loaders as sold in today's market. (I'm talking off the rack and not custom guns.)
First, a lot of the early, traditional guns were imports from countries where the US dollar had strong buying power. That situation has now reversed. Sometime in the late 90's the prices of Italian guns began taking off and have never really looked back. I like the Tryon rifle, but won't spend over $1,000 for a new "deluxe" model, thank you.
Second, I think that the BP community was a bit small compared to gun owners, as a whole. Maybe the market for traditional guns had become saturated and companies like T/C and CVA, along with importers like Navy Arms and Dixie, found they could only do so much volume. Along comes the in-line and a whole new market niche opens up. One that is potentially bigger. So production numbers favor the in-lines over the traditional designs, which now suffer sales loss to the "latest thing".
Third, in-lines are really pretty cheap to make. They have to be if CVA can retail some of their latest stuff for $150 and still make a profit. So the domestic manufacturers lose sight of what made them standouts in the first place, shiftingg practically all of their emphasis on the new generation guns and powders/bullets. It's a lot like golf, really. Not many companies making tour blades these days when everyone wants perimeter weighted designs that make the game "easier". Ditto fishing gear. It's easy for a marketer to convince people to "step up" to "cutting edge technology", along with all the doo-dads that go along with it. For example, look at the "evolution" of in-line ignition systems. First there was standard percussion cap, then primers, then improved (210?) primers. Got a regular breech? Let me "upgrade" you to a 3-way combo breech. Oh, Lord, how the money rolls in. Meanwhile, Mr. Hawkin's sales are down, again, so we had better turn him out to pasture.
Fortunately, there were enough people in the 70's, 80's and 90's who bought a T/C Hawken or CVA Mountain Rifle, shot it once upon a time, then put it away. Otherwise, we'ld all be broke! :haha: