I quess it's a concious choice that you are only able to upgrade a finite number of items in a single playthrough, to have the player commit to certain choices. It also makes different playthroughs more appealing since you can make choices you didn't in your last playthrough. Or maybe it is because they wanted to remove the notion of farming (although I think a fair bit of players find themselves 'farming' gold in ship encounters, even if normal questing is as effective if not more).
'Commit to choices' for most players = never use upgrades until they think they have the best items in the game
Is that a good way to design a crafting system, do you think?
When at first I played PoE I found it frustrating for that exact reason. Now during my first playthrough of PoE 2 however, I try to have a more relaxed attitude. I'm only playing on Veteran difficulty without the most outrageous modifiers/challenges, so I will beat the game without having to over-optimize. I will just stick with equipment I like. In a sense, it's kind of a liberating feeling that I don't have to keep a lookout for the most overpowered stuff and keep optimizing, I'll just enjoy the game and roll with the punches.
It would be different playing on max difficulty with the extra challenges/modifiers, but then you're at a point when you'll have to start meta gaming anyway.