Ah, the ancient battle of gameplay vs realism. Spoiler: Gameplay wins.
Yes, it does not make sense realistically that 3 coins take up the same space as a pistol. However, it makes perfect sense gameplay wise. And as stated above, gameplay always wins, and therefore, it should stay as it is and is perfect.
Are you serious? First off, going with your suggestion, i would be able to start with those items in my list. Unlike the 10 hammers. Secondly, the items in my list are amongst the strongest and most useful weapons/tools, especially the coins are already stupidly powerful. Hammers are not. Does not matter if you have 1 or 10 of them.
See the difference?