Does it curb your indignation at all to know that it is a work in progress and not the final intended product? This is just temporary. They will be adding new weapons to add variety and also adding location based gamestage modifiers which will increase both difficulty and loot levels. So if you are willing to risk the tougher biomes and POIs you will get better than blunderbusses for loot.
So you can either put up with it for the meantime or if it is so completely disagreeable you can take a break until they finish up this aspect of the game. There is also at least one mod I’ve heard about that returns the loot to completely random so there is that option too.