Just a thought, maybe flaming arrows and explosive ones weren't meant to be spammed?
Resources come and go. If a certain resource is scarce but you insist on being able to use it freely, it's the same way people get flat out bankrupt by their credit card irl isn't it?
How much TFP intends for the supply to be 'enough' is up in the air, that's why you're providing 'feedback', I'll leave it at that.
The only other point you raise is, there is perk for it, therefore it must be spammable. Feels weak.
As far as the argumentation goes, I'm not persuaded since you provided your feedback in an argumentative manner. Personally, for my crafting needs, plus regular shopping trips to the traders, it's covered. Not to the extent of excess but enough. Of course I don't 'spam' explosive bolts nor flaming arrows. The supply is too scarce for that, thus I make better choices.
I keep a small stock of them for horde night when they're bunched. And it's enough.
Maybe you play from the perspective that everything should be in easy supply in proportion to the effort put in to looking for them. Personally, I prefer the fact that some things will be in short supply no matter how hard you work for them.