Sure, but then one starts wondering if anybody would add some Schnabel or whatever bulge or ulcer to provide a good grip "just in case"?

IMO these "why" discussions can be lots of fun but are in the end "academic" because we do not know what the maker and the customer really thought and wanted back then...
Some stock shapes are clearly functional, but fashion also will play a role. And fashion will be repeated because it looks good or at some time "because that's the way it is done...."

Use of horn on a rifle is one such example. Really fashionable after Emperor Franz Joseph of Austria grew fond of rifles made by the gunmaker Leithner in Bad Ischl.
Example: http://www.hermann-historica.de/auktion/...;db=kat63_s.txt

Even today Austrian and German gunmakers build Ischlerstutzen!