I Believe it mostly is due to the price. A Bps in my neck of the woods runs between 550 and 650 new.(handled one at gander yesterday and they wanted 649.00). That's well over the price of a mossy 500 or rem 870. Not to mention it cost more than some semi auto shotguns like my mossberg 930(479.00). Now don't get me wrong they are very nice firearms, however at least in my case why spend so much on a pump action when you can get a semi. I know Browning makes some very nice firearms but am a firm believer in that most of the price difference is just because the name they put on the receiver.
"Si vis pacem, para bellum". If you want peace, Prepare for war!!!!