Hi Ernie,
If those "fancy" guns were never used. why were most converted to percussion? Why convert a gun you never used. Also keep in mind, many of the now flint guns, had been converted to percussion, then reconverted to flint in the 20th century. A surviving long rifle with its original flintlock is a real prize. Heck, there are quite a few rifles made as percussion that now sport flintlocks! There are many surviving plain long rifles, mostly from the 19th century but very few 18th century guns. The majority of surviving 18th century long rifles have some decoration, not necessarily fancy or extensive, but decoration nonetheless. There are a few surviving rifles without patch boxes but the majority, even the simple ones, have them. I believe it was an expected feature on rifles at the time.
dave