I didn't use any charms and only a couple malachite gems when I played through DKS as an archer (I suspect I might need more healing auras if I ever get around to playing an unarmed warrior, though). I used enchantment ingredients, but if you don't need them there is no reason to. I played on nightmare and stopped distributing stat points after level 15; had that not been enough to keep things interesting, I probably would have stopped using certain types of armour rather than not use enchantments.
I used more alchemy ingredients than I needed to, mostly to free up inventory space before getting the battle tower and have spare potions just in case I ran into trouble. I probably would have been fine with just looted potions. Actually, after I got the battle tower I ended up selling a bunch of different sized healing and rejuvenation potions potions I had collected to clean up my inventory and only focus on the largest potions I could make; I didn't need potions frequently, but when I did there wasn't any point being stingy with them (after the beginning of the game, anyway).
