I think for a single player game, a designer working of crafting should always have 2 questions at the front of his or her mind:
1) How easy is it for the player to find the exact same item?
2) How likely is this item to be sold rather than used?
DOS2 failed on both grounds (or if they had a good weapon or armor recipe I never found it). BG2 succeeded on the first (the artifacts were not replicable) and you were bound to use at least some of the items for a while.
One other consideration is customization: how many times have you found a cool item that you didn't really want to use because it's the wrong weapon? I suppose it's less of an issue in 5E, but in editions with "weapon specialization" type proficiencies/feats it was an issue. Gathering adamantine ingots, dragon's blood, and a gem taken from the heart of an earth elemental, taking it to a smith and being given the option of whether it's a sword, an axe or a hammer would be a nice change from "crap, if that wasn't a 2 handed weapon I'd be all over that"
Armour of the Eternals was solid for a good while. Also, the Vulture crafted set from the Relics of Rivellon was good, but that was kind of a "gimme" and just a consequence of the questline. Outside of those two specific instances, nothing else was worth crafting over what could be found, unfortunately.