Yes, it IS strange that there's been so little innovation in firearms technology since the introduction of cartridges in the 1870's and of smokeless powder in the 1880's. I suppose we could say that's a tribute to how well what we have now works.
Pinfires ARE an odd sort of contraption, aren't they? and to think they predate modern-style cartridges by decades, yet never replaced percussion. I own a little 8mm pinfire revolver: often wonder what stories it could tell.
Jim