The assumption that utility grade products cannot have any artistic or collection merit is, I think, wrong. For anyone interested the reasons are set out in this article on art influences in shotgun design:http://oplognosia.com/?p=9471
It is interesting that American collector interest focuses almost exclusively on what were mediocre attempts (not my opinion, see DIggory and others on that score) to copy European guns made for a very small minority of Europeans who indulged in driven game shooting. European production intended for the majority included some very crude crap, like Belgian folding guns and boxlock scrap grade shotguns that cannot stand comparison to affordable American guns of the same period.
Maybe there are US collectors who appreciate the Art Deco lines and mechanical ingenuity of 1920s shotguns, but so far I have not come across any. Personally I would rank a Stevens 620 way above any Belgian scrap grade boxlock from the 1930s even if it has the model name "Gamekeepa" on the barrels.