I was surprised to see BG3 has such a basic crafting system. It's a clear downgrade from D:OS2 which is odd, but perhaps understandable because of moving to 5e.
Still, it's not unfixable. What needs to happen first is to get rid of the vendor exploits (so that we can no longer buy hundreds of potions, arrows, elixirs, etc in one single long rest) and increase their price. Honestly, the price increase should happen without any crafting added since you can easily finish the game on Tactician with over 90k gold still in inventory even without making use of Pickpocketing.
Alchemy is honestly too much, we can craft VERY powerful potions and in great numbers. Having a potion of Detect Thoughts (doesn't even need concentration, by the way!) should be rare and powerful. There should be some sort of investment for crafting potions and elixirs - why did you get rid of the empty potion bottle requirement from D:OS2? Why don't we need an alchemy kit to craft outside of camp / labs? Why is it that everyone else has alchemy labs in their basement with all kinds of equipment needed for alchemy, but we can just press 2 buttons and create anything? At least include Tool proficiencies and Alchemy Kits!
The obvious things to be able to craft are different kinds of arrows (magical and otherwise). Why is it so incredibly hard to find Barbed or Piercing arrows right now? Non-magical arrows would be great for crafting. Creating arrows isn't simple (you need quality shafts, good feathers and different kinds of tips) but that's really just a bonus - you get lots of useful items to populate containers with. It's going to feel really nice to get into the blacksmith's house in Blighted Village and find a ton of arrowheads, maybe some shafts, etc. Pillows will finally see use again in obtaining feathers
The next obvious thing to add would be crafting scrolls. Right now scrolls are way too easy to obtain (again, partly due to how vendors work but also just because there's too many of them in containers). Mages being able to craft scrolls is a staple downtime activity in D&D, we should have it in some shape or form.
If we get player housing / camp customization, crafting furniture can be a thing.
Rope should get some use in game, grapplings hooks and rope ladders come to mind. We should be able to craft non-magical things that help with this otherwise achieved by magic - Feather Fall, for example. D:OS2 had more examples of this and I can't understand why they aren't in the game. Why can't we craft additions to our boot soles (to avoid slipping on ice, for example) or upgrades to our armor (rare stuff, maybe through quests)?
The Adamantium Forge is nice, combining found components is nice, finding a blueprint for a masterwork weapon was great but the masterwork weapon stops being useful real quick - we should have had a way to upgrade it later on. More of this kind of kind of crafting will suffice for blacksmithing imo - we're adventurers, not blacksmiths.